U.S. patent application number 12/748126 was filed with the patent office on 2010-09-30 for system and method for orthopedic measurement and alignment.
Invention is credited to Martin Roche.
Application Number | 20100249791 12/748126 |
Document ID | / |
Family ID | 42781940 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100249791 |
Kind Code |
A1 |
Roche; Martin |
September 30, 2010 |
SYSTEM AND METHOD FOR ORTHOPEDIC MEASUREMENT AND ALIGNMENT
Abstract
At least one embodiment is directed to a system for distracting
bones of a muscular-skeletal system. The dynamic distractor (100)
comprises at least one sensor (108, 110), a handle (112, 804), a
lift mechanism (302), and one or more alignment aids (502, 802).
The position and measurement sensors (108, 110) are in
communication with the processing unit (406) to display, process,
and store measured data. The process of distraction separates two
components such as bones of the muscular-skeletal system. Dynamic
distractor (100) can aid in the alignment of the skeletal system
and to verify that alignment is correct. A surface or feature on a
handle of dynamic distractor (100) has a relational position to one
of the surfaces being distracted. The surface has an optimal
alignment to a mechanical axis. An alignment aid (502, 802) is
coupled to the surface or feature to measure alignment to the
mechanical axis.
Inventors: |
Roche; Martin; (Fort
Lauderdale, FL) |
Correspondence
Address: |
Orthosensor, Inc.
1560 Sawgrass Corporate Pkwy, 4th Floor
Sunrise
FL
33323
US
|
Family ID: |
42781940 |
Appl. No.: |
12/748126 |
Filed: |
March 26, 2010 |
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Application
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61211023 |
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61221761 |
Jun 30, 2009 |
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Current U.S.
Class: |
606/90 ; 606/102;
606/86R |
Current CPC
Class: |
A61F 2/4657 20130101;
A61B 5/1076 20130101; A61B 2017/00221 20130101; A61B 2090/064
20160201; A61B 2017/0268 20130101; A61B 5/412 20130101; A61B 5/4509
20130101; G16H 70/60 20180101; A61F 2002/4668 20130101; A61F
2002/4666 20130101; G16H 20/40 20180101; A61B 5/4528 20130101; A61B
17/025 20130101; A61F 2002/4658 20130101 |
Class at
Publication: |
606/90 ;
606/86.R; 606/102 |
International
Class: |
A61B 17/56 20060101
A61B017/56 |
Claims
1. An orthopedic system comprising: a device coupled to a
muscular-skeletal system; a surface or feature on the device having
a relational position to at least one of surface of the
muscular-skeletal system where the surface or feature is used to
determine alignment with a mechanical axis of the muscular-skeletal
system.
2. The system of claim 1 where the device includes: a spacer having
a superior surface and an inferior surface to distract two surfaces
of the muscular-skeletal system; a handle coupled to the spacer
where the handle includes the surface or feature; and an alignment
aid coupled to surface or feature of the handle.
3. The system of claim 2 where the alignment aid coupled to the
surface or feature of the handle is used to determine misalignment
between the at least one surface of the muscular-skeletal system
and a mechanical axis of the muscular-skeletal system.
4. The system of claim 3 further including a sensor coupled to the
spacer for determining a relative position of at least two bones of
the muscular-skeletal system.
5. The system of claim 1 where the alignment aid comprises a rod,
where the feature is an opening or cavity, where the rod is
directed perpendicular to a plane of the at least one surface of
the muscular-skeletal system.
6. The system of claim 5 where the rod corresponds to an alignment
of the at least one surface to the mechanical axis.
7. The system of claim 5 where the rod includes at least one sensor
to measure a parameter of the muscular-skeletal system.
8. The system of claim 2 where the alignment tool comprises: at
least one laser coupled to the surface or feature of the handle;
and at least one target coupled to the muscular-skeletal system
where the at least one target is positioned to be in alignment with
the mechanical axis.
9. The system of claim 8 where the laser is directed perpendicular
to a plane of the at least one surface of the muscular-skeletal
system.
10. The system of claim 2 further including at least one sensor
overlying a superior or inferior surface of the spacer to measure
at least one parameter of the muscular-skeletal system.
11. The system of claim 10 where a spacing between the superior
surface and the inferior surface is adjustable in height and where
the handle can be moved away from a surgical area.
12. A method of measuring the muscular-skeletal system comprising
the steps of: distracting two surfaces of the muscular-skeletal
system with a spacer; and measuring misalignment of a surface of
the two surfaces to a mechanical axis with an alignment aid coupled
to a handle of the spacer block where the alignment aid is coupled
to a surface or feature on the handle that has a relational
position to the surface.
13. The method of claim 12 further including the steps of: placing
the two surfaces of the muscular-skeletal system in a first
position; correcting misalignment of the surface if outside a
predetermined range; measuring a gap between the two surfaces;
measuring a force applied by the two surfaces on the spacer; and
transmitting measurement data to a processing unit.
14. The method of claim 12 further including the steps of: placing
the two surfaces of the muscular-skeletal system in a second
position; checking alignment of the surface to the mechanical axis
in the second position; measuring a gap between the two surface in
the second position; measuring a force applied by the two surfaces
on the distractor in the second position; and transmitting
measurement data to the processing unit.
15. The method of claim 12 where the step of measuring misalignment
further includes the steps of: coupling at least one laser to the
handle; and coupling at least one target to the muscular-skeletal
system where a location of the beam hitting the target corresponds
to the misalignment of the surface to the mechanical axis.
16. An orthopedic system comprising: a dynamic distractor having a
superior surface and an inferior surface to variably distract at
least two surfaces of the muscular-skeletal system where either the
superior or inferior surface includes a sensor for measuring at
least one parameter of the muscular-skeletal system; and a handle
coupled to the distractor where the handle has at least one feature
having a relational position to a surface of the at least two
surfaces of the muscular-skeletal system to aid in determining
misalignment to a mechanical axis of the muscular-skeletal
system.
17. The system of claim 16 where the relational position of the
feature is perpendicular to a plane of the at least one surface of
the muscular-skeletal system.
18. The system of claim 17 where a center of the feature is aligned
to the mechanical axis.
19. The system of claim 16 where the feature is an opening or a
cavity in the handle, where a rod is coupled to the feature to
indicate a direction perpendicular to the at least one surface of
the muscular-skeletal system, and where the direction of the rod is
compared to the mechanical axis to determine misalignment.
20. The system of claim 16 further including: at least one laser
coupled to the feature of the handle; and at least one target
coupled to the muscular-skeletal system where the at least one
target is positioned to be in alignment with the mechanical axis.
Description
CROSS-REFERENCE
[0001] This application claims the priority benefits of U.S.
Provisional Patent Application No. 61/211,023 filed on Mar. 26,
2009, the entire contents of which are hereby incorporated by
reference. This application further claims the priority benefit of
U.S. provisional patent applications No. 61/221,761, 61/221,767,
61/221,779, 61/221,788, 61/221,793, 61/221,801, 61/221,808,
61/221,817, 61/221,867, 61/221,874, 61/221,879, 61/221,881,
61/221,886, 61/221,889, 61/221,894, 61/221,901, 61/221,909,
61/221,916, 61/221,923, and 61/221,929 all filed 30 Jun. 2009. The
disclosures of which are incorporated herein by reference in its
entirety.
FIELD
[0002] The disclosure relates in general to orthopedics, and
particularly though not exclusively, is related to a device and
method to facilitate orthopedic surgery.
BACKGROUND
[0003] The skeletal system is a balanced support framework subject
to variation and degradation. Changes in the skeletal system can
occur due to environmental factors, degeneration, and aging. An
orthopedic joint of the skeletal system typically comprises two or
more bones that move in relation to one another. Movement is
enabled by muscle tissue and tendons attached to the skeletal
system of the joint. Ligaments hold and stabilize the one or more
joint bones positionally. Cartilage is a wear surface that prevents
bone-to-bone contact, distributes load, and lowers friction. The
spinal column is comprised of vertebrae, discs, ligaments, and
muscles that stabilize the vertebral column and protects the spinal
nerves.
[0004] There has been substantial growth in the repairing of the
human skeletal system as orthopedic joint implant technology has
evolved. In general, improvements to orthopedic implant joints have
been based on empirical data that is sporadically gathered from
real patients. Similarly, the majority of implant surgeries are
being performed with tools that have not changed substantially in
decades but have been refined over time. In general, the orthopedic
implant procedure has been standardized to meet the needs of the
general population. Adjustments due to individual skeletal
variations rely on the skill of the surgeon to adjust the process
for the exact circumstance. At issue is that there is little or no
data during an orthopedic surgery, post-operatively, and long term
that provides feedback to the orthopedic manufacturers and surgeons
about the implant status.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Exemplary embodiments will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0006] FIG. 1 is a top view of a dynamic distractor in accordance
with an exemplary embodiment;
[0007] FIG. 2 is a side view of a dynamic distractor having a
minimum height in accordance with an exemplary embodiment;
[0008] FIG. 3 is a view of a dynamic distractor opened for
distracting two surfaces from each other in accordance with an
exemplary embodiment;
[0009] FIG. 4 is an anterior view of a dynamic distractor placed in
a knee joint in accordance with an exemplary embodiment;
[0010] FIG. 5 is a lateral view of dynamic distractor in a knee
joint positioned in flexion in accordance with an exemplary
embodiment;
[0011] FIG. 6 is a lateral view of a dynamic distractor in a knee
joint coupled to a cutting block in accordance with an exemplary
embodiment;
[0012] FIG. 7 is an anterior view of a cutting block coupled to
dynamic distractor in accordance with an exemplary embodiment;
[0013] FIG. 8 is an illustration of dynamic distractor including
alignment in accordance with an exemplary embodiment;
[0014] FIG. 9 is a side view of a leg in extension with a dynamic
distractor in the knee joint region in accordance with an exemplary
embodiment;
[0015] FIG. 10 is a top view of a leg in extension with a dynamic
distractor in the knee joint area in accordance with an exemplary
embodiment;
[0016] FIG. 11 is an illustration of a system for measuring one or
more parameters of a biological life form in accordance with an
exemplary embodiment;
[0017] FIG. 12 depicts an exemplary diagrammatic representation of
a machine in the form of a computer system within which a set of
instructions, when executed, may cause the machine to perform any
one or more of the methodologies discussed above;
[0018] FIG. 13 is an illustration of a communication network for
measurement and reporting in accordance with an exemplary
embodiment;
[0019] FIG. 14 is an exemplary method for distracting surfaces of
the muscular-skeletal system in accordance with an exemplary
embodiment;
[0020] FIG. 15 is an exemplary method for distracting surfaces of
the muscular-skeletal system in extension and in flexion in
accordance with an exemplary embodiment;
[0021] FIG. 16 is an exemplary method for distracting surfaces of
the muscular-skeletal system in extension and in flexion in
accordance with an exemplary embodiment;
[0022] FIG. 17 is an exemplary method for distracting surfaces of a
knee joint in extension and in flexion in accordance with an
exemplary embodiment;
[0023] FIG. 18 is an exemplary method to place the
muscular-skeletal system in a fixed position for bone shaping in
accordance with an exemplary embodiment;
[0024] FIG. 19 is an exemplary method of measuring the
muscular-skeletal system in accordance with an exemplary
embodiment;
[0025] FIG. 20 is an exemplary method of a disposable orthopedic
system in accordance with an exemplary embodiment; and
[0026] FIG. 21 is an exemplary method of a disposable orthopedic
system in accordance with an exemplary embodiment.
DETAILED DESCRIPTION
[0027] The following description of exemplary embodiment(s) is
merely illustrative in nature and is in no way intended to limit
the invention, its application, or uses.
[0028] Processes, techniques, apparatus, and materials as known by
one of ordinary skill in the art may not be discussed in detail but
are intended to be part of the enabling description where
appropriate. For example specific computer code may not be listed
for achieving each of the steps discussed, however one of ordinary
skill would be able, without undo experimentation, to write such
code given the enabling disclosure herein. Such code is intended to
fall within the scope of at least one exemplary embodiment.
[0029] Additionally, the sizes of structures used in exemplary
embodiments are not limited by any discussion herein (e.g., the
sizes of structures can be macro (centimeter, meter, and size),
micro (micrometer), nanometer size and smaller).
[0030] Notice that similar reference numerals and letters refer to
similar items in the following figures, and thus once an item is
defined in one figure, it may not be discussed or further defined
in the following figures.
[0031] In all of the examples illustrated and discussed herein, any
specific values, should be interpreted to be illustrative only and
non-limiting. Thus, other examples of the exemplary embodiments
could have different values.
[0032] In general, successful orthopedic surgery including the
implantation of an orthopedic device into the muscular-skeletal
system depends on multiple factors. One factor is that the surgeon
strives to maintain adequate alignment of the extremity or
implanted device to the ideal. A second factor is proper seating of
an implant for stability. A third factor is loading on the skeletal
system or replacement implant. A fourth factor is alignment of
implanted components in relation to one another. A fifth factor is
balance of loading over a range motion.
[0033] By way of a device herein contemplated, the surgeon receives
measured data during surgery and post operatively on the factors
listed above. As one example, accurate measurements can be made
during orthopedic surgery to determine if bones or an implant are
optimally balanced and aligned. This can reduce operating time and
surgical stress for both the surgeon and patient. The data
generated by direct measurement can be further processed to assess
long-term integrity based on maintaining surgical parameters within
predetermined ranges. The measured data in conjunction with patient
information can lead to improved design and materials.
[0034] FIG. 1 is a top view of a dynamic distractor 100 in
accordance with an exemplary embodiment. Dynamic distractor 100 is
also known as a dynamic spacer block. Dynamic distractor 100 is a
sensored device that is used during surgery of a muscular-skeletal
system. Dynamic distractor 100 can be used in conjunction with
other tools common to orthopedic surgery as will be disclosed in
more detail hereinbelow. In at least one exemplary embodiment, the
system is used during orthopedic joint surgery and more
specifically during implantation of an artificial joint. The system
uses one or more sensors intra-operatively to define implant
loading, positioning, achieve appropriate implant orientation,
balance, and limb alignment. In particular, dynamic distractor
combines the ability to align and measure one or more other
parameters (e.g. load, blood flow, distance, etc. . . . ) that
provides quantitative data to a surgeon that allows the orthopedic
surgery to be measured and adjusted within predetermined values or
ranges based on the measured data and a database of other similar
procedures. The system is designed broadly for use on the skeletal
system including but not limited to the spinal column, knee, hip,
ankle, shoulder, wrist, articulating, and non-articulating
structures.
[0035] Dynamic distractor 100 comprises an upper support structure
and a lower support structure. An active or dynamic spacer portion
120 of dynamic spacer block comprises the upper and lower support
structures. A lift mechanism (not shown) couples to an interior
surface of upper support structure and an interior surface of the
lower support structure. A handle 112 couples to the lift
mechanism. In one embodiment, handle 112 is operatively coupled to
the lift mechanism to change a gap of the spacer block. Handle 112
can also be used to guide dynamic distractor 100 between regions of
the muscular-skeletal system. In general, the upper support
structure has a superior surface 102 that interfaces with a surface
of the muscular-skeletal system. Similarly, the lower support
structure has an inferior surface that interfaces with a surface of
the muscular-skeletal system.
[0036] In one embodiment, handle 112 can be rotated to adjust the
lift mechanism to increase or decrease a gap between the superior
and inferior surfaces of the active spacer block thereby modifying
the height or thickness of dynamic distractor 100. In a
non-limiting example to illustrate a disposable aspect, superior
surface 102, the inferior surface, or both surfaces include at
least one cavity or recess for housing at least one sensor module.
The sensor module includes at least one sensor for measuring a
parameter of the muscular-skeletal system. For example, the sensor
can measure a force or pressure. As will be disclosed hereinbelow,
the sensor can be disabled so it cannot be reused and disposed of
after the procedure has been performed. In a further example,
dynamic distractor 100 can be placed between two or more bone
surfaces such that the superior surface 102 and the inferior
surface contact surfaces of the muscular-skeletal system related to
a joint. In one embodiment, the sensor is coupled to a surface of
the muscular-skeletal system for measuring a parameter when
positioned between surfaces. Handle 112 can be rotated to different
gap heights allowing pressure measurements at the different gap
heights to generate data of gap versus pressure.
[0037] Handle 112 further includes an opening 114, a decoupling
mechanism 118, and a display 116. Opening 114 is used to receive
additional components of the system that will be described in more
detail hereinbelow. Decoupling mechanism 118 allows removal of the
handle during parts of a surgery to allow access to the
muscular-skeletal system. Decoupling mechanism 118 couples to a
locking mechanism that locks handle 112 to a shaft of the lift
mechanism. Decoupling mechanism 118 releases the locking mechanism
thereby allowing handle 112 to be removed from dynamic distractor
100. In one embodiment, the locking mechanism is a pin or ball that
fits into a corresponding feature 122 on the shaft of the lift
mechanism. Decoupling mechanism 118 releases or frees the pin or
ball from feature 1122 thereby allowing removal of handle 112.
Alternatively, decoupling mechanism 118 can be a hinge or joint
that allows handle 112 to move in a direction that allows greater
access by the surgeon to an area where the spacer block portion of
dynamic distractor 100 has been placed. The display 116 on handle
112 can provide a readout of the gap between the superior surface
102 and the inferior surface as handle 112 is rotated to adjust
spacing.
[0038] In a non-limiting example, dynamic distractor 100 is adapted
for use in artificial knee implant surgery. It should be noted that
dynamic distractor 100 can be similarly adapted for other
orthopedic surgery where both distraction and parameter measurement
is beneficial. A knee implant is used merely as an example to
illustrate how dynamic distractor 100 can be used in a surgical
environment. In at least one exemplary embodiment, the superior
surface 102 of dynamic distractor 100 includes a recess or cavity
104 and a second recess or cavity 106. In one embodiment, a sensor
108 and a sensor 110 are pre-sterilized in one or more packages.
The packaging is opened prior to or during surgery within the
surgical zone to maintain sterility. Sensors 108 and sensor 110 are
shown respectively placed in cavities 104 and 106 for measuring a
parameter that aids in the surgical procedure. In the knee example,
sensors 108 and 110 include pressure sensors such as strain gauges,
mechanical-electrical-machined (mems) sensors, diaphragm
structures, mechanical sensors, or other pressure measuring
devices. In one embodiment, a major exposed surface of sensors 108
and 110 is in contact with the muscular-skeletal system after
insertion. Alternatively, one or more layers of material or
portions of the muscular-skeletal system can be between sensors 108
and 110 such that the parameter can be measured or transferred
through the intervening layers. A force or pressure applied to the
exposed surfaces is measured by sensors 108 and 110 while the gap
of the dynamic distractor is adjusted. Alternatively, the lift
mechanism in conjunction with sensors 108 and 110 can be set to a
predetermined pressure. The lift mechanism gap will increase until
the predetermine pressure is reached. Thus, identifying a gap
height or thickness of dynamic distractor 100 to achieve the
predetermined pressure.
[0039] In at least one exemplary embodiment, sensors 108 and 110
are disposable devices. After measurements have been taken, sensors
108 and 110 can be removed and disposed of in an appropriate
manner. Alternatively, the sensors 108 and 110 can be permanent or
an integral part of the superior surface of dynamic distractor 100.
The housing can be designed to be reused and to withstand a
sterilization process after each use. The main body of dynamic
distractor 100 as well as sensors 108 and 110 are cleaned and
sterilized before each surgical usage.
[0040] Dynamic distractor 100 in a zero gap (or closed condition)
is less than 8 millimeters thick for the knee application and can
expand using the lift mechanism to greater than 25 millimeters.
This range is sufficient for the majority of artificial knee
implant surgeries being performed. The spacer portion 120 of
dynamic distractor 100 contains the superior surface 102 and the
inferior surface that articulates to at least two bone ends of the
muscular-skeletal system. In the knee example, the dynamic
distractor 100 is placed between the distal end of the femur and
the proximal end of the tibia. As mentioned previously sensors 108
and 110 are in a housing. In one embodiment, the housing includes
sensor elements to define the loads on the medial and lateral
compartments. The sensored elements can comprise load displacement
sensors, accelerometers, GPS locators, telemetry, power management
circuitry, a power source and an ASIC.
[0041] As disclosed above, the spacer portion 120 of dynamic
distractor 100 is placed between the femur and tibia in extension.
The dynamic distractor 100 is configured with no gap (e.g. minimum
height or thickness) or having a gap that can be inserted and
removed without tissue damage. In general, the gap can be increased
by rotating handle 112 after insertion such that the inferior
surface of dynamic distractor 100 contacts a prepared surface of a
proximal end of a tibia and the superior surface contacts the
prepared distal end of the femur. In general, the femoral and
tibial cuts in extension are made parallel to one another.
Similarly, the femoral cut in flexion is made parallel to the
prepared end of the tibia. The gap is measured to determine a
combined thickness of the implants with the leg in extension. The
prepared ends of the tibia and femur can be checked for alignment
with the mechanical axis at this time as will be disclosed in
detail below.
[0042] Typically, the surgeon selects the artificial components
based on the cross-sectional size of the prepared bones. The
variable component of the implant surgery is the final insert. The
final insert has one or more bearing surfaces for interfacing with
a femoral implant. In one embodiment, the measured gap height
created by dynamic distractor 100 is used to define an insert
thickness or height. The thickness of a final insert can change
during surgery as further bone cuts or tissue tensioning occurs.
Dynamic distractor 100 can be used during surgery to measure
loading and gap height after each bone modification or after an
orthopedic component has been implanted.
[0043] Dynamic distractor 100 can also be used to obtain an optimal
balance. Balance is related to the measured loading between two or
more areas. The measured values can than be adjusted to a
predetermined relationship and within a predetermined value range.
In the knee example, balance is associated with the differential
pressure applied by each condyle on the bearing surfaces of the
implant. Ideally, a predetermined surface area of the femoral
implant condyle contacts the bearing surface to distribute the load
and minimize wear. In a non-limiting example, a predetermined
relationship between measured values by sensors 108 and 110 of
dynamic distractor 100 is maintained after implantation of the
artificial components. In one embodiment, the balance of the knee
is maintained by having the measured load in each compartment
approximately equal. A method to balance the loading of the
compartments is through ligament release on the side having the
larger loading value. Ligament release reduces loading primarily on
the adjacent compartment. The loading can be read off a display on
dynamic distractor 100 allowing the surgeon to view the change in
loading and the differential value with each release. The lift
mechanism provides sufficient room between the superior and
inferior surfaces of dynamic distractor 100 for a surgeon to
perform a release procedure without removing the device. A next
greater thickness of an insert can be selected should the absolute
loading value on each condyle fall outside the predetermined range
due to the soft tissue release. Handle 112 can be rotated to
increase the gap height to the next larger insert value to ensure
the measured loading falls within the predetermined range and the
differential loading falls within a predetermined range (after the
soft tissue release).
[0044] The loading and balance of an implanted joint should be
maintained within the predetermined values throughout the range of
motion. In at least one exemplary embodiment, measurements are
taken when the tibia is at a ninety-degree angle to the femur.
Handle 112 is used to position the spacer block portion of
distractor 100 between the femur and the tibia. The inferior
surface of dynamic distractor 100 is in contact with the prepared
surface of the tibia. In one embodiment, the superior surface 102
is in contact with the remaining portion of the condyles of the
femur. Thus, the condyle surfaces of the femur are in contact with
sensors 108 and 110 on the superior surface of dynamic distractor
100. In the example, a gap height of dynamic distractor 100 is
reduced to accommodate the condyles that remain on the distal end
of the femur in flexion. The gap height of dynamic distractor 100
can then be adjusted to a height corresponding to the gap height in
extension less the thickness of the femoral implant whereby the leg
in flexion is similar to the leg in extension.
[0045] The loading on sensors 108 and 110 with the leg in flexion
can be measured. The measurement is of value if the condyles are
not damaged or degraded. In one embodiment, soft tissue release is
used to adjust the balance between compartments with the leg in
flexion. The soft tissue release can also be performed later in the
procedure after the femoral implant has been implanted. Similar to
the leg in extension, soft tissue release is performed to reduce
the tension on the side having the higher compartment reading with
dynamic distractor 100 in place. After soft tissue release, the
readings in each compartment should be within a predetermined
differential range. The distal end of the femur can then be
prepared for receiving the femoral implant, which removes the
remaining portion of the condyles. As disclosed, the surface of the
femur is prepared to be parallel to the prepared tibial surface in
flexion. This can be achieved by specific ligament releases in
flexion, and/or rotation of the femoral implant to achieve a
parallel levels between the posterior femoral condyles and proximal
tibia. A femoral sizer can be attached to the distractor to allow
sizing of the femur, coupled with rotation of the femur. This
allows dynamic rotation to obtain equally balanced flexion
compartments.
[0046] In a non-limiting example, the femoral implant component can
be temporarily attached to the distal end of the femur.
Measurements can be taken throughout the entire three-dimensional
range of motion using dynamic distractor 100 to ensure that the
implanted knee operates similarly in all positions. A gap provided
by dynamic distractor 100 would be adjusted to a combined thickness
of the final insert thickness and the tibial implant thickness.
Dynamic distractor 100 can incrementally increase or decrease the
gap to allow the surgeon to determine how different insert
thicknesses affect load and balance measurements. In one
embodiment, accelerometers are used to provide position and
relational positioning information. The data can be stored in
memory for later use or displayed to provide instant feedback to
the surgeon on the implant status. Further adjustments to load and
balance can be made with dynamic distractor in place if desired
over different positions within the range of motion. Although one
implant sequence is disclosed, it is well known that surgeons have
different approaches, methodologies and procedure sequences. The
use of dynamic distractor 100 would be applied similarly to
distract and measure in different relational positions with the
device in place. Furthermore, the device can be used or modified
for use on different parts of the anatomy of the muscular-skeletal
system.
[0047] FIG. 2 is a side view of dynamic distractor 100 having a
minimum height in accordance with an exemplary embodiment. Dynamic
distractor comprises an upper support structure 202 having superior
surface 102 and a lower support structure 204 having an inferior
surface 206. In the example, upper support structure 202, the lift
mechanism, and lower support structure 204 supports loading typical
for a joint of the muscular-skeletal system. Upper and lower
support structures 202 and 204 comprise a rigid and load bearing
materials such as metals, composite materials, and plastics that
will not flex under loading. In one embodiment, stainless steel is
used in the manufacture of the lift mechanism and upper and lower
support structures 204 and 202.
[0048] Dynamic distractor 100 is used to distract surfaces of the
muscular-skeletal system. Dynamic distractor 100 can be used in an
invasive procedure such as orthopedic surgery. In the non-limiting
example, dynamic distractor 100 can distract surfaces of the
muscular-skeletal system in a range of approximately 8 millimeters
to 25 millimeters. The support surfaces of dynamic distractor 100
do not flex under loading of the muscular-skeletal system. In one
embodiment, dynamic distractor 100 has a minimum height or
thickness between support surfaces of less than 8 millimeters. In
at least one application, a space between support structures 202
and 204 is provided when dynamic distractor 100 is opened to a
height greater than the minimum height. The space between support
structures 202 and 204 when opened allows a surgeon to perform soft
tissue release with the device in place.
[0049] A cavity 104 is illustrated in superior surface 102 of upper
support structure 202. The cavity 104 is shaped similarly to a
housing 210 of sensor 108. Housing 210 is placed within cavity 108
for measuring a compressive force applied across superior surface
102 and inferior surface 206. In the knee example, a condyle
(implanted or natural) couples to an exposed surface of sensor 108.
A pressure or force applied to sensor 108 is measured and displayed
by dynamic distractor 100. Sensor 110 is shown placed in its
corresponding cavity in superior surface 102. In one embodiment,
the exposed surfaces of sensors 108 and 110 are approximately
planar to the superior surface 102. The exposed surface of sensor
108 and 110 can be flat or contoured. Sensors 108 and 110 can be
removed from upper support structure 202 and disposed after the
surgery has been performed. In one embodiment, a push rod is
exposed in the interior surface of upper support structure 202 that
when pressed can apply a force to housing 210 that removes sensor
108 from cavity 208
[0050] In one embodiment, housing 210 is formed of a plastic
material. The sensor and electronic circuitry is fitted in housing
210. The electronic circuitry comprises one or more sensors 220,
one or more accelerometers 222, an ASIC integrated circuit 224, a
power source 226, power management circuitry 228, GPS circuitry
230, and telemetry 232. The power source 226 can be a battery or
other temporary power source that is coupled to the electronic
circuitry prior to surgery. The power source 226 has sufficient
power to enable the circuitry for a period of time that will cover
the vast majority of surgeries. The power management circuitry 228
works in conjunction with the power source to maximize the life of
the power source by disabling system components when they are not
being used. In general, an ASIC circuit controls and coordinates
when sensing occurs, can store data to memory, and can transmit
data in real time or collect and send data at a more appropriate
time to a remote system for further processing. The ASIC includes
multiple ports that couple to one or more sensors 220. The ASIC
couples, to at least one sensor 220, at least one accelerometer
222, GPS 232, and telemetry circuitry 232. The ASIC 222 can include
the integration of telemetry circuitry 232, power management
circuitry 228, GPS circuitry 230, memory, and sensors 220 to
further reduce the form factor of the sensing system. In the
example, the at least one sensor 220 is a pressure sensor that is
coupled to the exposed surface of the housing. The pressure sensor
converts the pressure to an electrical signal that is received by
the ASIC. The at least one accelerometer 222 and GPS 232 provides
positioning information at the time of sensing. Telemetry circuitry
232 communicates through a wired or wireless path. In one
embodiment, the data is sent to a remote processing unit that can
process and display information for use by the surgeon or medical
staff. One or more displays 234 can be placed on dynamic distractor
100 to simplify viewing of a pressure or force measured by sensors
108 and 110 thereby allowing real time loading and balance
differential to be seen at a glance. The information can be stored
in memory on the sensor or transmitted to a database for long-term
storage and processing.
[0051] In a zero gap or minimum height condition, the lift
mechanism is enclosed within the device. An opening 212 exposes a
threaded rod 216 that is a component of the lift mechanism. The
exposed end portion of threaded rod 216 is shaped for receiving
handle 112. For example, a proximal end 214 of handle 212 is shown
having a hexagonal opening that operatively couples to a hexagonal
shaped end of threaded rod 216. The surfaces of the hexagonal
surface mate with the surfaces of the threaded rod for distributing
the torque required to rotate threaded rod 216 when increasing a
gap between superior surface 102 and inferior surface 206 to
distract surfaces of the muscular-skeletal system. Distributing the
torque over a large surface area prevents stripping of either the
hexagonal shaped opening of handle 212 or the hexagonal shaped
exposed end of threaded rod 216 when the device is under load. In
one embodiment, a release and locking mechanism fastens handle 112
to threaded rod 216. Pressing or sliding unlocking button 218
releases the locking mechanism to allow removal of handle 112.
[0052] FIG. 3 is a view of dynamic distractor 100 opened for
distracting two surfaces of the muscular-skeletal system in
accordance with an exemplary embodiment. A lift mechanism 302
comprises a scissor mechanism 304 for raising and lowering upper
support structure 202 and lower support structure 204. In one
embodiment, scissor mechanism 304 comprises more than one support
structure each having a pivot. Scissor mechanism 304 is operatively
coupled to an interior surface of upper support structure 202 and
an interior surface of lower support structure 204. The structural
beams are pinned to allow pivoting around the axis of attachment.
The remaining beam-ends rest on the interior surfaces of either the
upper and lower support structures 202 and 204. The beam-ends not
fastened to the interior surfaces support upper and lower support
structures 202 and 204 under load. Threaded rod 212 is operatively
coupled between the beam-ends of scissor mechanism 304
corresponding to lower support structure 204. Rotating rod 212 can
increase or decrease distance between beam ends of the scissor
mechanism 204.
[0053] A rod 306 can be coupled to opening 114 of handle 112. The
rod 306 can be used to reduce the torque needed to rotate threaded
rod 212 in either direction under load. Increasing a distance
between beam-ends of scissor mechanism 304 reduces the gap between
superior surface 102 and inferior surface 206 as the two or more
beams pivot around a centrally located axis. Conversely, decreasing
a distance between beam-ends of scissor mechanism 304 increases the
gap between superior surface 102 and inferior surface 206.
[0054] FIG. 4 is an anterior view of a dynamic distractor 100
placed in a knee joint in accordance with an exemplary embodiment.
In the non-limiting example, a distal end of a femur 102 is shown
having a femoral implant. The femoral implant has artificial
condyles that contact sensors 108 and 110. The proximal end of a
tibia 404 has been initially shaped for receiving a tibial implant.
As is well known by one skilled in the art, a complete knee implant
comprises the tibial implant, the femoral implant, and an insert
that includes bearing surfaces that mate with the artificial
condyle surfaces of the femoral implant. In one embodiment, dynamic
distractor (100) includes an adjustable handle 112 that aids in the
insertion of the spacer portion into a joint region of the
muscular-skeletal system. For example, the spacer portion of
dynamic distractor 100 is inserted into the knee joint using handle
112 but then rotated away from the patellar tendon, collapsed into
the trail, or removed to allow the reduction of the patella to
depict loads on the instrument. The thickness or height of the
three components is contemplated for the bone surface preparation
when using dynamic distractor 100. In one embodiment, the combined
thickness of the femoral implant, final insert, and tibial implant
is approximately 20 millimeters thick. Adjustments to the prepared
bone surfaces and thickness of the insert are made during surgery
using data provided by dynamic distractor 100 to ensure correct
loading, balance, and alignment.
[0055] Sensors 108 and 110 include circuitry for communication with
a processing unit 406. In one embodiment, data is sent wirelessly
using a radio frequency communication standard such as Bluetooth,
UWB, or Zigbee. The data can be encrypted to securely transmit the
patient information and maintain patient privacy. In one
embodiment, external processing unit 406 is in a notebook computer,
personal computer, or custom equipment. For illustration purposes,
external processing unit 406 is shown in a notebook computer that
includes software and a GUI designed for the surgical application.
The notebook computer has a display 408 that can be used by the
medical staff during the operation to display real time measurement
from dynamic distractor 100. The notebook computer is typically
placed outside the surgical zone but within viewing range of the
surgeon.
[0056] A substantial benefit of dynamic distractor 100 is in
performing soft tissue release both in extension and in flexion. In
extension, dynamic distractor 100 can be set to a height
corresponding to an insert size. In one embodiment, manufacturers
of an implantable joint will provide specifications for load,
balance, and alignment once sufficient clinical data has been
generated. The surgeon can also manipulate the leg to subjectively
gauge the loading on the joint. The surgeon can adjust dynamic
distractor 100 to increase or decrease the height or gap
corresponding to a different thickness insert size until a desired
loading is achieved. A substantial imbalance corresponds to a
differential loading measured by sensors 108 and 110 outside a
predetermined range. The loading measured by sensors 108 and 110
should be approximately equal in each compartment. The data
provided by sensors 108 and 110 can be used to provide a solution
to the surgeon. For example, data from sensors 108 and 110 is sent
wirelessly to processing unit 406. The data indicates a substantial
differential pressure between measurements from sensors 108 and 110
(e.g. imbalance). In one embodiment, the data can be processed and
displayed on display 408 with suggestions for the removal of
material from the tibial surface to reduce the differential
reading. The suggestion can include where material should be
removed and how much material is removed from the tibial surface.
Alternatively, the assessment of the loading and differential
between compartments can indicate that soft tissue release is
sufficient to bring the joint within predetermined ranges for
absolute load and balance.
[0057] A further benefit of dynamic distractor 100 is in soft
tissue release to modify loading measured by sensors 108 and 110
and the differential (e.g. balance) between the measured values in
each compartment. Dynamic distractor 100 remains in place while
soft tissue release is being performed allowing for real time
measurement and modification to occur. The feedback to the surgeon
is immediate as the soft tissue cuts are made. Two issues are
resolved by dynamic distractor 100. An open area formed between the
interior surfaces of upper support structure 202 and lower support
structure 204 under distraction provides surgical access. In most
cases, the gap is sufficient to allow a scalpel or blade access to
the lateral or medial ligaments for soft tissue release in the gap
or peripheral to dynamic distractor 100. In general, soft tissue
release requires anterior access to the joint space. Handle 112 of
dynamic distractor 100 can be removed providing further anterior
access to the joint. Alternatively, handle 112 is hinged or
includes a joint allowing it to be positioned away from the
surgical area. Thus, dynamic distractor 100 enables soft tissue
release by the surgeon to adjust the absolute loading measured by
sensors 108 and 110 in each compartment to be within a
predetermined range and to adjust the difference in compartment
loadings within a predetermined range without removing the
device.
[0058] FIG. 5 is a lateral view of dynamic distractor 100 in a knee
joint positioned in flexion in accordance with an exemplary
embodiment. In a non-limiting example, load and balance
measurements are performed using dynamic distractor 100 with the
leg in at least two positions (e.g. the leg in extension and the
leg in flexion). For example, measurements are taken in extension
as disclosed hereinabove and in flexion with the leg positioned
having femur 402 forming a 90 degree angle to tibia 404. In one
embodiment, accelerometers in sensors 108 and 110 are used to
determine relative positioning of the femur and tibia to one
another. Under user control, measurements are taken at several
points over the range of motion with dynamic distractor 100 in
place thereby substantially simplifying a data collection process.
Measurements over the range of motion can be taken when the femoral
implant has been installed or if the distal femur has not been
modified. Alternatively, dynamic distractor 100 can be reduced in
height by rotating handle 112 until there is sufficient room to
move the leg to a new position and then increasing the height of
distractor 100 to create the appropriate gap.
[0059] A drop alignment rod 502 is placed through opening 114 of
handle 112. Drop alignment rod 502 is a visual aid for the surgeon
to ensure that the leg is aligned adequately when the load and
balance measurements are taken. Drop alignment rod 502 is used in
conjunction with a knowledge of the leg mechanical axis or with
markers placed on the patient to check alignment. The surgeon
aligns alignment rod 502 to the leg mechanical axis and makes a
subjective determination that the leg is correctly positioned. The
surgeon can increase accuracy by pre-identifying points on the
mechanical axis. The surgeon has the option of making adjustments
if drop alignment rod 502 indicates a potential positional error.
Drop alignment rod 502 can be tapered having a section with a
greater width than opening 114 to retain it in place and prevent it
from falling through. Other embodiments to retain drop alignment
rod 502 can also be used.
[0060] Alternatively, drop alignment rod 502 can be a smart
alignment aid for the surgeon that incorporates electronics similar
to that described in FIG. 2. In general, drop alignment rod
includes sensors to allow depiction of the mechanical axis. For
example, drop alignment rod 502 can incorporate sensors to identify
position in three-dimensional space. The electronics would allow
drop alignment rod 502 to communicate with pre-operative defined
locations or locations that are identified at the time of surgery
using locator electronics. The drop rod can house light emitters to
depict an axis as will be discussed in more detail hereinbelow. The
electronics can include communication to external processing unit
406 with a graphic user interface that has the mechanical axis
loaded therein.
[0061] FIG. 6 is a lateral view of a dynamic distractor 100 in a
knee joint coupled to a cutting block 602 in accordance with an
exemplary embodiment. In general, the surgeon utilizes surgical
tools to obtain appropriate bony cuts to the skeletal system. The
surgical tools are often mechanical devices used to achieve gross
alignment of the skeletal system prior to or during an implant
surgery. In the knee example, mechanical alignment aids are often
used during orthopedic surgery to check alignment of the bony cuts
of the femur and tibia to the mechanical axis of the leg. The
mechanical alignment aids are not integrated together, take time to
deploy, and have limited accuracy. Dynamic distractor 100 in
concert with cutting block 602 is an integrated system for
achieving alignment that can greatly reduce set up time thereby
minimizing stress on the patient.
[0062] As illustrated, the leg is in flexion having a relational
position of 90 degrees between femur 402 and tibia 404. A femoral
rod 608 is coupled through the intermedullary canal of femur 402. A
cutting block 602 is attached to the femoral rod 608 for shaping a
portion of the surface of the distal end of femur 402 for receiving
a femoral implant. Knee replacement surgery entails cutting bone a
certain thickness and implanting a prosthesis to allow pain relief
and motion. During the surgery, instruments are used to assist the
surgeon in performing the surgical steps appropriately. Dynamic
distractor 100 aids the surgeon by allowing quantitative
measurement of the gap and parameter measurement during all stages
of the procedure. For the knee, the data can supplement a surgeon's
"feel" by providing data on absolute loading in each compartment,
the load differential between compartments, positional information,
and alignment information.
[0063] The portion of the surface of the distal end of femur 402 in
contact with dynamic distractor 100 is shaped in a subsequent step.
In a non-limiting example, the portion of the condyles in contact
with superior surface 102, sensor 108, and sensor 110 are the
natural condyles of the femur. The portion of the distal end of
femur 402 being shaped corresponds to the condyle portion that
would be in contact with the final spacer while the leg is in
extension and partially through the range of motion. In at least
one exemplary embodiment, an uprod 604 of dynamic distractor 100
couples to cutting block 602. Uprod 604 aids in the alignment of
the cutting block 602 to dynamic distractor 100 and tibia 404.
Uprod 604 further stabilizes cutting block 602 to prevent movement
as the distal end of femur 402 is shaped.
[0064] In one embodiment, handle 112 is removed and an uprod 604 is
attached to threaded rod 212. The uprod 604 can include a hinge
that positions rod 604 vertically to mate with cutting block 602.
Alternatively, handle 112 can include a hinge. In this example,
handle 112 is uprod 604 and is inserted into cutting block 602.
Furthermore, uprod 604 can be fastened or coupled to an opening or
feature in handle 112 to couple to cutting block 602. In general,
uprod 604 is placed at a right angle to the inferior surface of
lower support structure 204 of dynamic distractor 100. In a prior
step, the leg alignment can be checked to ensure it is within a
predetermined range of the mechanical axis. In one embodiment,
uprod 604 aligns approximately to the mechanical axis to secure
cutting block 602 in an appropriate geometric orientation. Cutting
block 602 includes a channel 606 for receiving uprod 604. Uprod 604
can be adjustable in length that simplifies insertion. As
previously mentioned, uprod 604 is attached to dynamic distractor
100 to align with the mechanical axis of the leg corresponding to
tibia 404. Fitted in the opening and into channel 606, uprod 604
maintains a positional relationship between cutting block 602,
dynamic spacer block 100, femur 402, and tibia 404. More
specifically, the proximal surface of tibia 404 is aligned to the
mechanical axis thereby fixing the position of femur 402 and
cutting block 602 in a similar fixed geometric relational position.
Thus, the distal end of femur 402 is cut having surfaces parallel
to the proximal tibial surface by coupling dynamic distractor 100
to cutting block 602 through uprod 604.
[0065] FIG. 7 is an anterior view of a cutting block 602 coupled to
dynamic distractor 100 in accordance with an exemplary embodiment.
Cutting block 602 is attached to the distal end of femur 402.
Femoral rod 608 extends through cutting block 602 into the
intermedullary canal. Uprod 604 is shown extending vertically into
channel 606 of cutting block 602. In combination, femoral rod 608
and uprod 604 prevent movement and maintain alignment of the
cutting block to the leg mechanical axis. As shown, cutting block
602 is illustrated as rectangular in shape. Cutting block 602 is
shaped to form a predetermined bone shape on the distal end of
femur 402 for receiving a femoral implant. Thus, the shape of
cutting block 602 can vary significantly from that shown depending
on the implant. The size of the cutting block 602 corresponds to
the distal end size and the femoral implant selected by the
surgeon. The surgeon uses a bone saw to remove portions of the
distal end of femur 402 in conjunction with cutting block 602. In
general, the cutting block 602 acts as a template to guide the bone
saw and to cut the distal end of the femur in a predetermined
geometric shape. As disclosed previously in the example, the
portion of the distal end of femur 404 that is shaped corresponds
to the contact portion of the condyles when the leg is in full
extension and partially in flexion (e.g. <90 degrees). As
mentioned previously, the portion of the distal end of femur 402 in
contact the superior surface 102 of dynamic distractor 100 is
shaped in a subsequent step.
[0066] FIG. 8 is an illustration of dynamic distractor 100
including alignment in accordance with an exemplary embodiment.
Dynamic distractor 100 includes one or more recesses 802 in a
handle 804 for receiving an alignment aid to align a leg along the
mechanical axis. In one embodiment, handle 804 can be handle 112
that includes recesses 802. Alternatively, handle 804 is a separate
handle for dynamic distractor 100. Prior to checking alignment,
handle 112 is removed from dynamic distractor 100. Handle 804 is
coupled to threaded rod 212.
[0067] Initial bony cuts are made in alignment with the mechanical
axis of the leg. In the knee example, the alignment aid is used to
check that the femur and the tibia are correctly oriented prior to
cutting. The surfaces of the bones are cut in alignment to the
mechanical axis using a jig. Thus, the cut surfaces on the distal
end of the femur and the proximal end of the tibia are aligned and
can be used as a reference surfaces during the procedure.
Alternatively, the alignment aid can be used to verify alignment
throughout the procedure. Recesses 802 can be thru-holes in handle
804. In a non-limiting example, the alignment aid is one or more
lasers 808. Lasers 808 are used to point along the mechanical axis
of the leg. In one embodiment, lasers 808 are used to check
alignment of the leg. A first laser is used to point in the
direction of the hip joint. A second laser is used to point towards
the ankle. In one embodiment, the first and second lasers are
integrated into a single body. Handle 804 further comprises a hinge
806 to change the angle at which lasers 808 are directed. The
housing of lasers 808 includes a power source such as a battery to
generate the monochromatic light beam. The housing fits within one
of recesses 802 or a thru-hole. Lasers 808 can be a disposable item
that is discarded after the surgery is completed.
[0068] FIG. 9 is a side view of a leg in extension with dynamic
distractor 100 in the knee joint region in accordance with an
exemplary embodiment. The mechanical axis of the leg is
approximately a straight line from the center of the femoral head
through the knee joint and extending to the middle of the ankle
joint. In a correctly aligned knee joint, the mechanical axis will
pass approximately through the center of the knee joint. Alignment
can be checked when dynamic distractor 100 is positioned in the
knee joint region. As illustrated, the leg is in extension with
handle 804 extending vertically from the knee joint region. In one
embodiment, a target 902 is placed in an ankle or toe region of the
foot in a path corresponding to center of the ankle on the
mechanical axis of the leg. Similarly, a target 904 is placed in a
path corresponding to the center of the head of the femur on the
mechanical axis of the leg. Targets 902 are placed at a height
similar to that of lasers 808. Lasers 808 are installed in the
handle with one pointing in the direction of the hip joint and
another pointing in the direction of the ankle joint. From the top
view, lasers 808 send out a beam of light from a position that
corresponds to the center of the knee. In one embodiment, the
direction of the beam from lasers 808 is directed perpendicular to
a plane of the prepared surface of the proximal end of the
tibia.
[0069] Lasers 808 are directed perpendicular to the inferior
surface of dynamic distractor 100. The placement of dynamic
distractor 100 on the prepared tibial surface is such that handle
804 extends vertically at a point corresponding to the center of
the knee joint. The leg is aligned correctly when the beams from
lasers 808 hit the target at the points corresponding to the center
of the head of the femur and the center of the ankle. Lasers 808
are positioned to align with the center of the knee joint. The
surgeon can make adjustments to the bone surfaces or utilize soft
tissue release to achieve alignment with the leg mechanical axis
when lasers 808 are misaligned to the target. The system can be
used to give a subjective or a measured determination on leg
alignment in relation to a vargus or valgus alignment. The
direction of misalignment in viewing targets 902 and 904 will
dictate the type of correction and how much correction needs to be
made. In an alternate embodiment, lasers 808 can be aimed such that
the beam is viewable along the leg in a region by the center of the
femoral head and the center of the angle. The surgeon can use this
as a subjective visual gauge to determine if the leg is in
alignment to the mechanical axis and respond appropriately,
depending on what is viewed.
[0070] FIG. 10 is a top view of a leg in extension with dynamic
distractor 100 in the knee joint area in accordance with an
exemplary embodiment. Dynamic distractor 100 can measure spacing
between the distal end of the femur and the tibia, loading in each
compartment, and differential loading between compartments. The
data can be sent to a processing unit and display as disclosed
hereinabove. As mentioned previously, the mechanical axis of the
leg corresponds to a straight line from the center of the ankle,
through the center of the knee, and the center of the femoral head.
Targets 902 and 904 are respectively located overlying the
mechanical axis in an area local to the ankle and the hip regions.
Targets 902 and 904 can include a fixture such as a strap, brace,
or jig to hold the targets temporarily along the mechanical axis.
Lasers 808 are enabled and placed in handle 804. The figure
illustrates that targets 902 and 904 are on approximately the same
plane as beams emitted by lasers 808 such that the beams impinge on
a target unless grossly misaligned. Targets 902 and 904 can include
calibration markings to indicate a measure of the misalignment.
Alternatively, handle 804 is hinged allowing adjustment of the
angle at which the beam from lasers 808 is directed. The direction
of the lasers 808 corresponds to the plane of the bone cuts for the
implant and the balance of the joint. Thus, the surgeon using a
single device has both quantitative and subjective data relating to
alignment to the mechanical axis, loading, balance, leg position,
and gap measurement that allows gross/fine tuning during surgery
that results in more consistent orthopedic outcomes.
[0071] FIG. 11 is an illustration of a system 1100 for measuring
one or more parameters of a biological life form in accordance with
an exemplary embodiment. In a non-limiting example, the system
provides real time measurement capability to a surgeon of one or
more parameters needed to assess a muscular-skeletal system. System
1100 comprises a plurality of spacer blocks 1102, a distractor
1104, sensors 1106, targets 1110, lasers 1114, a charger 1116, a
receiver 1118, a reader 1120, a processing unit 1122, a display
1124 a drop rod 1126, an uprod 1128, a cutting block 1130, a handle
1132, a dynamic data repository and registry 1134. The system is
adaptable to provide accurate measurements of parameters such as
distance, weight, strain, pressure, wear, vibration, viscosity, and
density to name but a few. In one embodiment, system 1100 is used
in orthopedic surgery and more specifically to provide
intra-operative measurement during joint implant surgery. System
1100 is adapted for orthopedic surgery and more specifically for
knee surgery to illustrate operation of the system.
[0072] In general, system 1100 provides alignment and parameter
measurement system for providing quantitative measurement of the
muscular-skeletal system. In one embodiment, system 1100 is
integrated with tools commonly used in orthopedics to reduce an
adoption cycle to utilize new technology. System 1100 replaces
standalone equipment or dedicated equipment that is used only for a
small number of procedures that justifies the extra time and set up
required to use this type of equipment. Furthermore, it is well
known, that dedicated equipment can cost hundreds of thousands or
millions of dollars for a single device. Many hospitals and other
healthcare facilities cannot afford the high capital cost of these
types of systems. Moreover, specialized equipment such as robotic
systems or alignment systems for orthopedic surgery typically has a
large footprint. The large footprint creates space and cost issues.
The equipment must be stored, set up, calibrated, placed in the
operating room, and then removed.
[0073] Conversely, measurement and alignment components of system
1100 are low cost disposables that make the measurement technology
more accessible to the general public. There is no significant
capital investment required to use the system. Moreover, payback
begins immediately with use in providing quantitative information
related to procedures thereby allowing analysis of outcomes based
how the parameters being measured affect the procedure being
measured. The data is used to initiate predetermined specifications
for the procedure that can be measured and adjusted during the
course of the procedure thereby optimizing the outcomes and
reducing revisions. As mentioned previously, system 1100 can be
used or integrated with tools that the majority of orthopedic
surgeons have substantial experience or familiarity using on a
regular basis. In one embodiment, sensors 1106 are placed in a
spacer that separates two surfaces of the muscular-skeletal system.
In a non-limiting example, the spacer can be spacer blocks 1102 or
distractor 1104. A measurement of the parameter is taken after the
spacer is inserted between at least two surfaces of the
muscular-skeletal system. Sensors 1106 are in communication with
processing unit 1122. In one embodiment, the processing unit 1122
is outside the sterile field and includes display 1124 and a GUI to
provide the data in real time to the surgeon. Thus, the learning
cycle can be very short to provide real time quantitative feedback
to the surgeon as well as storing the data for subsequent use.
[0074] In a non-limiting example a spacer separates two surfaces of
the muscular-skeletal system. The spacer has an inferior surface
and a superior surface that contact the two surfaces. The spacer
can have a fixed height or can have a variable height. The fixed
height spacer is known as spacer blocks 1102. Each spacer block
1102 has a different thickness. The variable height spacer is known
as the distractor 1104. The surface area of spacer blocks 1102 and
distractor 1104 that couple to the surfaces of the
muscular-skeletal system can also be provided in different sizes.
The handle 1132 extends from the spacer and typically resides
outside or beyond the two surface regions. The handle 1132 is used
to direct the spacer between the two surfaces. In one embodiment,
the handle 1132 operatively couples to a lift mechanism of the
distractor 1104 to increase and decrease a gap between the superior
and inferior surfaces of the spacer. The spacer and handle 1132 is
part of system 1100 to measure alignment of the muscular-skeletal
system. In one embodiment, at least one of the surfaces of the
muscular-skeletal system that contacts the spacer has an optimal
alignment to a mechanical axis of the muscular-skeletal system. The
system measures the surface to mechanical axis alignment. In a
non-limiting example, the misalignment can be corrected by a
surgeon when the surface is misaligned to the mechanical axis
outside a predetermined range as disclosed below.
[0075] Knee replacement surgery entails cutting bone having a
predetermined spacing and implanting a prosthesis to allow pain
relief and motion. During the surgery, instruments are used to
assist the surgeon in performing the surgical steps appropriately.
The majority of surgeons continue to use passive spacers to aid in
defining the gaps between the cut bones. The thickness of the final
insert is selected after placing one or more trial inserts in the
artificial joint implant. The determination of whether the
implanted components are correctly installed is still to a large
extent by "feel" of the surgeon through movement of the leg. In
general, spacer blocks 1102 and distractor 1104 of system 1100 is a
spacer having an inferior and superior surface that separate at
least two surfaces of the muscular-skeletal system. In the knee
example, the inferior and superior surfaces are inserted between
the femur and tibia of the knee. At least one of the inferior or
superior surfaces of spacer blocks 1102 and distractor 1104 have a
cavity or recess for receiving sensors 1106. In one embodiment, the
cavity is on the superior surface of spacer blocks 1102 and
distractor 1104. A gap between the surfaces of distractor 1104 is
adjustable as described hereinabove. Tray 1108 includes multiple
spacer blocks 1102 each having a different thickness. Thus, spacer
blocks 1102 and distractor 1104 provide the surgeon with more than
one option to measure spacing, alignment, and loading during the
procedure. A benefit of the system is the familiarity that the
surgeon will have with using similar type devices thereby reducing
the learning curve to utilize system 1100. Furthermore, system 1100
can comprise spacer blocks 1102 and distractor 1104 having spacer
blocks having different sized superior and inferior surface areas
to more readily accommodate different bone shapes and sizes.
[0076] In general, a rectangle is formed by the bony cuts during
surgery. The imaginary rectangle is formed between the cut distal
end of a femur and the cut proximal end of tibia in extension and
in conjunction with the mechanical axis of the lower leg. The
prepared surfaces of the femur and tibia are shaped to respectively
receive a femoral implant and a tibial implant. The femoral and
tibial surfaces are parallel to one another when the leg is in
extension and in flexion at 90 degrees. A predetermined width of
the rectangle is the spacing between the planar surface cuts on
femur and tibia. The predetermined width corresponds to the
thickness of the combined orthopedic implant device comprising the
femoral implant, an insert, and the tibial implant. A target
thickness for the initial cuts is typically on the order of twenty
millimeters. The insert is inserted between the installed femoral
implant and the tibial implant. In a full knee implant the insert
has two bearing surfaces that are shaped to receive the condyle
surfaces of the femoral implant.
[0077] In at least one exemplary embodiment, sensors 1106 can
measure load and position. Sensors 1106 are placed in a charger
1116 prior to the implant surgery being performed. Charger 1116
provides a charge to an internal power source within sensors 1106
that will sustain sensor measurement and data transmission
throughout the surgery. Charger 1116 can fully charge sensor 1106
or be used as a precautionary measure to insure the temporary power
storage is holding sufficient charge. Charger 1116 can be charge
via a wireless connection through a sterilized packaging. Sensors
1106 are in communication with processing unit 1122. Sensors 1106
include a transmitter for sending data. Processing unit 1122 can be
logic circuitry, a digital signal processor, microcontroller,
microprocessor, or part of a system having computing capability. As
shown, processing unit 1122 is a notebook computer having a display
1124. The communication between sensors 1106 and processing unit
1122 can be wired or wireless. In one embodiment, receiver 1118 is
coupled to processing for wireless communication. A carrier signal
for data transmitted from sensors 1106 can be radio frequency,
infrared, optical, acoustic, and microwave to name but a few. In a
non-limiting example, receiver 1118 receives data via a radio
frequency signal in a short range unlicensed band sufficient for
transmission within the size of an operating room. Information from
processing unit 1122 can be sent through the internet to dynamic
data repository and registry 1134 for long-term storage. The
dynamic data repository and registry 1134 will be discussed in
greater detail hereinbelow. In one embodiment, the data is stored
in a server 1136 or as part of a larger database.
[0078] The surgeon uses system 1100 to aid in the preparation of
bone surfaces, to measure loading, to measure balance, check
alignment, and tune the knee joint prior to a final insert being
installed. A reader 1120 is used to scan in information prior to or
during the surgery. In one embodiment, the reader 1120 can be wired
or wirelessly coupled to the processing unit 1122. Processing unit
1122 can process the information, display it on display 1124 for
use during a procedure, and store it in memory or a database for
long-term use. For example, information on components used in the
surgery such as the artificial knee components or components of
system 1100 can be converted to an electronic digital form using
reader 1120 during the procedure. Similarly, patient information or
procedural information can also be scanned in, input manually, or
captured by other means to processing unit 1122.
[0079] The leg is placed in extension and the knee joint is exposed
by incision. In one embodiment, the surgeon prepares the proximal
end of the tibia. The prepared tibial surface is typically at a
90-degree angle to the mechanical axis of the leg. Targets 1110 are
placed overlying the mechanical axis near the ankle and hip joint.
The surgeon can select one of the spacer blocks 1102 or dynamic
distractor 1104 for insertion in the joint region. The selected
spacer block has a predetermined thickness that is imprinted on the
spacer block or can be displayed on display 1124 by scanning the
information. Alternatively, distractor 1104 is distracted by the
surgeon within the joint region. The amount of distraction can be
read off of distractor 1104 or can be displayed on display
1124.
[0080] In a non-limiting example of aligning two surfaces of the
muscular-skeletal system, alignment of the leg to the mechanical
axis is measured or a subjective check can be performed by the
surgeon using an alignment aid. At least one component of the
alignment aid is disposable. The alignment aid comprises lasers
1114 in the handle 1112 of the selected spacer block or a handle
1132 of distractor 1104 with the leg in extension. The alignment
aid further includes targets 1110. Targets 1110, lasers 1114, or
both can be disposable. Accelerometers in sensors 1106 provide
positional information of the tibia in relation to the femur. For
example, display 1124 will indicate that the angle between the
tibia and femur is 180 degrees when the leg is in extension. The
beam from lasers 1114 hit targets 1110 and provides a measurement
of the position of the tibia in relation to the femur compared to
the mechanical axis of the leg. In one embodiment, lasers 1114 are
centrally located above the knee joint overlying the mechanical
axis of the leg. The beam from lasers 1114 is directed
perpendicular to the plane of the surface of the tibia. The beam
from lasers 1114 will align and overlie the mechanical axis if the
surface of the tibia is the perpendicular to the mechanical axis.
The beam from lasers 1114 would hit targets 1110 at a point that
indicates alignment with the mechanical axis. A valgus or vargus
reading can be read where the beam hits the calibrated markings of
targets 1110 if the leg is not aligned. The surgeon can then make
an adjustment to bring the leg into closer alignment to the
mechanical axis if deemed necessary. Jigs or cutting blocks can
also be used in conjunction with lasers 1114 and targets 1110 to
check alignment prior to shaping. The jigs or cutting blocks are
used to shape the bone for receiving an implant. The distal end of
femur and the proximal end of tibia are shaped for receiving
orthopedic joint implants. In a further embodiment, sensors can be
attached to the cutting jigs or devices to aid the surgeon in
optimizing the depth and angles of their cuts.
[0081] Sensors 1106 measure the loading in each compartment for the
depth or thickness of the selected spacer block or the distracted
gap generated by distractor 1104. In one embodiment, the loading
measurements are taken after the initial bone cuts are determined
to be within a predetermined range of alignment with the mechanical
axis. The load measurement in each compartment is either high,
within an acceptable predetermined range, or low. A load
measurement above a predetermined range can be adjusted by removing
bone material, selecting a thinner spacer block, adjusting the gap
of distractor 1104, or by soft tissue release. In general, the gap
between the femur and tibia at which the measurement taken
corresponds to a final insert thickness. In one embodiment, the gap
is selected to result in a load measurement on the high side of the
predetermined range to allow for fine-tuning through soft tissue
release. Conversely, a load measurement below the predetermined
range can be increased using the next thicker spacer block or by
increasing the gap of distractor 1104. Data from sensors 1106 is
transmitted to processing unit 1122. Processing unit 1122 processes
the data and displays the information on display 1124 for use by
the surgeon to aid in fine-tuning. Display 1124 would further
provide positional information of the femur and tibia. The absolute
loading in each compartment is measured and displayed on display
1124. As is known by one skilled in the art, the gap created by the
bone cuts accommodates the combined thickness of the femoral
implant, the tibial implant, and the insert. The gap using spacer
blocks 1102 or distractor 1104 takes into account the combined
thickness of the implant components. In a non-limiting example, the
gap is chosen based on the availability of different thicknesses of
the final insert. Thus, the loading on the final or permanent
insert placed in the joint will measure within the predetermined
range as prepared by using system 1100.
[0082] Balance is a comparison of the load measurement of each
condyle surface. In general, balance correction is performed when
the measurements exceed a predetermined difference value. Soft
tissue balancing is achieved by loosening ligaments on the side of
the compartment that measures a higher loading. In one embodiment,
system 1100 allows the surgeon to read the loading measurement for
each compartment on one or more displays on spacer blocks 1102 or
distractor 1104. Another factor is that the difference in loading
can be due to surface preparation of the bony cuts for either
femoral implant or the tibial implant. If the differential is
substantial, the surgeon has the option of removing bone on either
surface underlying the implant to reduce the loading
difference.
[0083] In one embodiment, the absolute load adjustments and balance
adjustments are performed by soft tissue release in response to the
assessment of each compartment. Load and balance adjustment is
achieved with the selected spacer block or distractor 1104 in the
knee joint. Spacer blocks 1102 and distractor 1104 have a gap to
provide peripheral access between the superior and inferior
surfaces of the device thereby giving the surgeon access to perform
soft tissue release to either compartment with real time load
measurement shown on display 1124. In at least one exemplary
embodiment, handles 1112 of spacer blocks 1102 or handle 1132 of
distractor 1104 can be removed or positioned. Handles 1112 or
handle 1132 can be positioned away from the surgical area or
removed allowing the surgeon access to perform soft tissue release.
The soft tissue release is performed to each compartment to adjust
the absolute loading within the predetermined range and further
adjustment can be performed to reduce the differential loading
between the compartments to within a predetermined differential
range. Consequently, the surgical outcome is a function of system
1100 as complemented with the surgeon's abilities but not so highly
dependent alone on the surgeon's skill. The device captures the
"feel" of how an implanted device should properly operate to
improve precision and minimize variation including haptic and
visual cues.
[0084] A similar process is applied with the lower leg in flexion
with tibia forming a 90-degree angle with the femur. In one
embodiment, one or more bone cuts are made to the distal end of
femur for receiving the femoral implant. The preparation of the
femur corresponds to the leg in extension. As disclosed above, the
selected spacer block or distractor 1104 can be coupled using an
uprod from handle 1112 or handle 1132 to cutting block 1130 to aid
in alignment and stability. In particular, the surface of the
distal end of femur is cut parallel to the prepared surface of the
tibia with the leg in flexion. The bone cut to the femur yields an
imaginary rectangle formed with the parallel surfaces of femur and
tibia when the leg is in extension. It should be noted that a
portion of the femoral condyle is in contact with the selected
spacer block or distractor 1104 with the leg in flexion and this
region is not prepared at this time. In a subsequent step, the
remaining surface of the distal end of the femur is prepared. The
width of the gap in extension and in flexion between the cut distal
end of the femur and the prepared tibia surface corresponds to the
thickness of the combined orthopedic implant device comprising the
femoral implant, final insert, the tibial implant. Ideally, the
measured the gap under equal loading in flexion (e.g. the tibia
forms a 90 degree angle with the femur) and extension is similar or
equal. The prepared femoral surfaces and the prepared tibial
surfaces are parallel throughout the range of motion and
perpendicular to the mechanical axis of the leg.
[0085] Load measurements are made with the leg in flexion and the
selected spacer block or distractor 1104 between the distal end of
the femur and the tibial surface. In a non-limiting example, the
measurements as described above should be similar to the
measurements made in extension. Adjustments to the load value and
the balance between compartments can be made by soft tissue
release, or femoral component rotation in flexion with the selected
spacer block or distractor 1104 in place. Alternatively, the
femoral implant can be seated on the distal end of the femur and
measurements taken. Adjustments can be made with the femoral
implant in place. Furthermore, a gap generated by distractor 1104
can be adjusted to accommodate differences due to the femoral
implant if required.
[0086] The leg with the selected spacer block or distractor 1104
can be taken through a complete range of motion. The loading in
each compartment can be monitored on display 1124 and processed by
processing unit 1122 over the range of motion. Processing unit can
compare different points in the range of motion to the
predetermined load range and the predetermined differential load
range. Should an out of range/value condition occur, the surgeon
can view and note the position of the femur and tibia position on
display 1124 and take steps to bring the implant within
specification. The surgeon can complete the implant surgery having
knowledge that both qualitative and quantitative information was
used during the procedure to ensure correct installation. In one
embodiment, sensors 1106, disposable targets 1110, and lasers 1114
are disposed of upon completion of the surgery.
[0087] For example, the sensors will enable the surgeon to measure
joint loading while utilizing soft tissue tensioning to adjust
balance and maximize stability of an implanted joint. Similarly,
measured data in conjunction with positioning can be collected
before and during surgery to aid the surgeon in ensuring that, the
implanted device has an equivalent geometry and range of
motion.
[0088] Element 1340 of FIG. 12 depicts an exemplary diagrammatic
representation of a machine in the form of a computer system 1200
within which a set of instructions, when executed, may cause the
machine to perform any one or more of the methodologies discussed
above. In some embodiments, the machine operates as a standalone
device. In some embodiments, the machine may be connected (e.g.,
using a network) to other machines. In a networked deployment, the
machine may operate in the capacity of a server or a client user
machine in server-client user network environment, or as a peer
machine in a peer-to-peer (or distributed) network environment.
[0089] The machine may comprise a server computer, a client user
computer, a personal computer (PC), a tablet PC, a laptop computer,
a desktop computer, a control system, a network router, switch or
bridge, or any machine capable of executing a set of instructions
(sequential or otherwise) that specify actions to be taken by that
machine. It will be understood that a device of the present
disclosure includes broadly any electronic device that provides
voice, video or data communication. Further, while a single machine
is illustrated, the term "machine" shall also be taken to include
any collection of machines that individually or jointly execute a
set (or multiple sets) of instructions to perform any one or more
of the methodologies discussed herein.
[0090] The computer system may include a processor (e.g., a central
processing unit (CPU), a graphics processing unit (GPU, or both), a
main memory and a static memory, which communicate with each other
via a bus. The computer system may further include a video display
unit (e.g., a liquid crystal display (LCD), a flat panel, a
solid-state display, or a cathode ray tube (CRT)). The computer
system may include an input device (e.g., a keyboard), a cursor
control device (e.g., a mouse), a disk drive unit, a signal
generation device (e.g., a speaker or remote control) and a network
interface device.
[0091] The disk drive unit may include a machine-readable medium on
which is stored one or more sets of instructions (e.g., software)
embodying any one or more of the methodologies or functions
described herein, including those methods illustrated above. The
instructions may also reside, completely or at least partially,
within the main memory, the static memory, and/or within the
processor during execution thereof by the computer system. The main
memory and the processor also may constitute machine-readable
media.
[0092] Dedicated hardware implementations including, but not
limited to, application specific integrated circuits, programmable
logic arrays and other hardware devices can likewise be constructed
to implement the methods described herein. Applications that may
include the apparatus and systems of various embodiments broadly
include a variety of electronic and computer systems. Some
embodiments implement functions in two or more specific
interconnected hardware modules or devices with related control and
data signals communicated between and through the modules, or as
portions of an application-specific integrated circuit. Thus, the
example system is applicable to software, firmware, and hardware
implementations.
[0093] In accordance with various embodiments of the present
disclosure, the methods described herein are intended for operation
as software programs running on a computer processor. Furthermore,
software implementations can include, but not limited to,
distributed processing or component/object distributed processing,
parallel processing, or virtual machine processing can also be
constructed to implement the methods described herein.
[0094] The present disclosure contemplates a machine readable
medium containing instructions, or that which receives and executes
instructions from a propagated signal so that a device connected to
a network environment can send or receive voice, video or data, and
to communicate over the network using the instructions. The
instructions may further be transmitted or received over a network
via the network interface device.
[0095] While the machine-readable medium is shown in an example
embodiment to be a single medium, the term "machine-readable
medium" should be taken to include a single medium or multiple
media (e.g., a centralized or distributed database, and/or
associated caches and servers) that store the one or more sets of
instructions. The term "machine-readable medium" shall also be
taken to include any medium that is capable of storing, encoding or
carrying a set of instructions for execution by the machine and
that cause the machine to perform any one or more of the
methodologies of the present disclosure.
[0096] The term "machine-readable medium" shall accordingly be
taken to include, but not be limited to: solid-state memories such
as a memory card or other package that houses one or more read-only
(non-volatile) memories, random access memories, or other
re-writable (volatile) memories; magneto-optical or optical medium
such as a disk or tape; and carrier wave signals such as a signal
embodying computer instructions in a transmission medium; and/or a
digital file attachment to e-mail or other self-contained
information archive or set of archives is considered a distribution
medium equivalent to a tangible storage medium. Accordingly, the
disclosure is considered to include any one or more of a
machine-readable medium or a distribution medium, as listed herein
and including art-recognized equivalents and successor media, in
which the software implementations herein are stored.
[0097] Although the present specification describes components and
functions implemented in the embodiments with reference to
particular standards and protocols, the disclosure is not limited
to such standards and protocols. Each of the standards for Internet
and other packet switched network transmission (e.g., TCP/IP,
UDP/IP, HTML, HTTP) represent examples of the state of the art.
Such standards are periodically superseded by faster or more
efficient equivalents having essentially the same functions.
Accordingly, replacement standards and protocols having the same
functions are considered equivalents.
[0098] The illustrations of embodiments described herein are
intended to provide a general understanding of the structure of
various embodiments, and they are not intended to serve as a
complete description of all the elements and features of apparatus
and systems that might make use of the structures described herein.
Many other embodiments will be apparent to those of skill in the
art upon reviewing the above description. Other embodiments may be
utilized and derived therefrom, such that structural and logical
substitutions and changes may be made without departing from the
scope of this disclosure. Figures are also merely representational
and may not be drawn to scale. Certain proportions thereof may be
exaggerated, while others may be minimized. Accordingly, the
specification and drawings are to be regarded in an illustrative
rather than a restrictive sense.
[0099] FIG. 12 and FIG. 13 illustrate a communication network 1300
for measurement and reporting in accordance with an exemplary
embodiment. Briefly, the communication network 1300 expands broad
data connectivity to other devices or services. As illustrated, the
measurement and reporting system 1300 can be communicatively
coupled to the communications network 1300 and any associated
systems or services.
[0100] As one example, the measurement system 1355 can share its
parameters of interest (e.g., angles, load, balance, distance,
alignment, displacement, movement, rotation, and acceleration) with
remote services or providers, for instance, to analyze or report on
surgical status or outcome. This data can be shared for example
with a service provider to monitor progress or with plan
administrators for surgical monitoring purposes or efficacy
studies. The communication network 1300 can further be tied to an
Electronic Medical Records (EMR) system to implement health
information technology practices. In other embodiments, the
communication network 1300 can be communicatively coupled to HIS
Hospital Information System, HIT Hospital Information Technology
and HIM Hospital Information Management, EHR Electronic Health
Record, CPOE Computerized Physician Order Entry, and CDSS
Computerized Decision Support Systems. This provides the ability of
different information technology systems and software applications
to communicate, to exchange data accurately, effectively, and
consistently, and to use the exchanged data.
[0101] The communications network 1300 can provide wired or
wireless connectivity over a Local Area Network (LAN) 1301, a
Wireless Local Area Network (WLAN) 1305, a Cellular Network 1314,
and/or other radio frequency (RF) system (see FIG. 4). The LAN 1301
and WLAN 1305 can be communicatively coupled to the Internet 1320,
for example, through a central office. The central office can house
common network switching equipment for distributing
telecommunication services. Telecommunication services can include
traditional POTS (Plain Old Telephone Service) and broadband
services such as cable, HDTV, DSL, VoIP (Voice over Internet
Protocol), IPTV (Internet Protocol Television), Internet services,
and so on.
[0102] The communication network 1300 can utilize common computing
and communications technologies to support circuit-switched and/or
packet-switched communications. Each of the standards for Internet
1320 and other packet switched network transmission (e.g., TCP/IP,
UDP/IP, HTML, HTTP, RTP, MMS, SMS) represent examples of the state
of the art. Such standards are periodically superseded by faster or
more efficient equivalents having essentially the same functions.
Accordingly, replacement standards and protocols having the same
functions are considered equivalent.
[0103] The cellular network 1314 can support voice and data
services over a number of access technologies such as GSM-GPRS,
EDGE, CDMA, UMTS, WiMAX, 2G, 3G, WAP, software defined radio (SDR),
and other known technologies. The cellular network 1314 can be
coupled to base receiver 1310 under a frequency-reuse plan for
communicating with mobile devices 1302.
[0104] The base receiver 1310, in turn, can connect the mobile
device 1302 to the Internet 1320 over a packet switched link. The
internet 1320 can support application services and service layers
for distributing data from the measurement system 1355 to the
mobile device 1302. The mobile device 1302 can also connect to
other communication devices through the Internet 1320 using a
wireless communication channel.
[0105] The mobile device 1302 can also connect to the Internet 1320
over the WLAN 1305. Wireless Local Access Networks (WLANs) provide
wireless access within a local geographical area. WLANs are
typically composed of a cluster of Access Points (APs) 1304 also
known as base stations. The measurement system 1355 can communicate
with other WLAN stations such as laptop 1303 within the base
station area. In typical WLAN implementations, the physical layer
uses a variety of technologies such as 802.11b or 802.11g WLAN
technologies. The physical layer may use infrared, frequency
hopping spread spectrum in the 2.4 GHz Band, direct sequence spread
spectrum in the 2.4 GHz Band, or other access technologies, for
example, in the 5.8 GHz ISM band or higher ISM bands (e.g., 24 GHz,
etc).
[0106] By way of the communication network 1300, the measurement
system 1355 can establish connections with a remote server 1330 on
the network and with other mobile devices for exchanging data. The
remote server 1330 can have access to a database 1340 that is
stored locally or remotely and which can contain application
specific data. The remote server 1330 can also host application
services directly, or over the internet 1320.
[0107] It should be noted that very little data exists on implanted
orthopedic devices. Most of the data is empirically obtained by
analyzing orthopedic devices that have been used in a human subject
or simulated use. Wear patterns, material issues, and failure
mechanisms are studied. Although, information can be garnered
through this type of study it does yield substantive data about the
initial installation, post-operative use, and long term use from a
measurement perspective. Just as each person is different, each
device installation is different having variations in initial
loading, balance, and alignment. Having measured data and using the
data to install an orthopedic device will greatly increase the
consistency of the implant procedure thereby reducing rework and
maximizing the life of the device. In at least one exemplary
embodiment, the measured data can be collected to a database where
it can be stored and analyzed. For example, once a relevant sample
of the measured data is collected, it can be used to define optimal
initial measured settings, geometries, and alignments for
maximizing the life and usability of an implanted orthopedic
device.
[0108] FIG. 14 is an exemplary method 1400 for distracting surfaces
of the muscular-skeletal system in accordance with an exemplary
embodiment. The method can be practiced with more or less than the
number of steps shown and is not limited to the order shown. In
general, a spacer can have a fixed height or can be variable. The
spacer is placed between surfaces of the muscular-skeletal system
to distract or separate the surfaces. The spacer can include a
handle to direct the spacer into the muscular-skeletal system. In
one embodiment, the spacer is used to separate a joint region. A
spacer with a fixed height is also known as a spacer block. A
spacer having variable height is known as a distractor. In one
embodiment, a distractor includes a lift mechanism as disclosed
herein that can precisely adjust a height between surfaces to
create a gap in the muscular-skeletal system of a predetermined
value. A dynamic distractor includes one or more sensors that can
measure a parameter of the muscular-skeletal system in real time. A
variable height spacer can comprise a predetermined height in one
state and a compressible height in a second state. The second state
allows compression of the spacer as the muscular-skeletal system is
moved from a first relational position to a second relational
position. The variable height spacer can then be fixed to the
predetermined height once positioned in the second relational
position.
[0109] In a step 1402, sterilized sensors are removed from
packaging. The sensors are powered up and enabled for sensing. One
or more sensors coupled to a sensor for measuring a parameter of
the muscular-skeletal system. For example, sensors are placed
overlying a superior surface of a dynamic distractor. In the
example, the sensors are used to measure load and balance for a
knee reconstruction procedure. In one embodiment, the sensors are
placed in a cavity on the superior surface of the distractor. Each
sensor corresponds to a compartment of the knee. The dynamic
distractor is also in a sterilized condition.
[0110] In a step 1404, the spacer is inserted in the
muscular-skeletal system. The surfaces of the spacer are in contact
with surfaces of muscular-skeletal system to be distracted. The
surfaces of the muscular-skeletal system are in a first relational
position. Continuing with the knee example, the inferior surface of
the dynamic distractor is coupled to the proximal end of the tibia
and the superior surface is coupled to the distal end of the femur.
In one embodiment, the distal end of the tibia is prepared having a
flat surface that is perpendicular to the mechanical axis of the
leg.
[0111] In a step 1406, a dynamic distractor is used to vary a gap
between the surfaces of the muscular skeletal system. In the knee
example, a handle coupled to a lift mechanism of the dynamic
distractor rotated to increase a gap between the inferior and
superior surfaces. As the gap increases the inferior surface is in
contact with the distal end of the tibia. Similarly, the superior
surface of the dynamic distractor contacts the distal end of the
femur. In one embodiment, the condyles of the distal end of the
femur or the condyles of a femoral implant contact the
corresponding sensors in each compartment of the dynamic
distractor. The dynamic distractor is placed in the knee joint such
that the dynamic distractor is centrally located in the knee joint.
In one embodiment, the mechanical axis of the leg aligns to a
feature of the dynamic distractor between the medial and lateral
sides of the device. The handle of the dynamic distractor extends
away from the knee joint on the mechanical axis of the leg.
[0112] In a step 1408, a parameter is measured by the sensors. The
parameter is a quantitative measurement such as distance, weight,
strain, force, load, pressure, wear, vibration, viscosity, and
density that relate and characterize the procedure being performed.
For illustration purposes the sensors measure load, pressure, or
force. In the knee example, the loading in each compartment of the
knee is measured at the height or gap created by the dynamic
distractor. Similarly, the parameter measurement can be taken using
the sensors overlying a spacer of a predetermined height. In one
embodiment, the gap or height of distraction relates to the
thickness of one or more components of an artificial joint such as
the knee joint. The gap can correspond to the thickness of a final
insert of the artificial joint. In general, final inserts typically
comprise a polymer that provide a low-friction low-wear bearing
surface. The final inserts are typically provided in a number of
predetermined thicknesses of which one is selected for permanent
insertion.
[0113] In a step 1410, the one or more sensors are removed from the
spacer. In general, the sensor is removed after all quantitative
measurements have been taken during the procedure. In a step 1412,
the sensor is disposed of after the procedure is completed. For
example, the sensors can be exposed to biological waste and require
disposal as a biological hazard. The sensors as a disposable item
alleviate substantial problems facing the health care industry. The
high capital cost of traditional of surgical equipment often
prevent purchase thereby preventing potentially beneficial
equipment from being used. Disposables also eliminate the costly
and time-consuming process of sterilization. The low cost of the
sensors eliminates the capital cost issue thereby opening
quantitative measurement of joint implants to a much larger
audience. The result will be more consistent surgeries, ability to
fine tune the surgery, longer implant life, and reduced post
surgical complications to name but a few.
[0114] In general, a modification to the muscular-skeletal, a
quantitative measurement, or both is performed with the surfaces of
the muscular-skeletal in more than one relational position. In one
embodiment, the surfaces of the muscular-skeletal system are
positioned in a first relational position. A modification to the
muscular-skeletal system is performed. The modification can affect
the parameter being measured. In a step 1436, the two surfaces are
positioned in a second relational position. In one embodiment, the
spacer is not removed during the process of repositioning the
surfaces of the muscular-skeletal system. A modification to the
muscular-skeletal system, a quantitative measurement, or both can
then be performed with the surfaces of the muscular-skeletal system
in the second relational position.
[0115] Steps 1414, 1416, and 1418 illustrates an optimization
process for a procedure with the dynamic distractor. In the knee
example, steps 1414, 1416, and 1418 are an adjustment to optimize
loading for a final insert of the artificial joint that maximizes
the operating life of the device. The leg is placed in a first
relational position. For example, the leg is placed in extension
with the femur and tibia aligned with a mechanical axis of the leg.
In general, it is not desirable for the implanted joint to be too
tight or loose. In a step 1414, the gap is increased until the
loading is within a predetermined loading range and the gap
corresponds to an available final insert thickness. In one
embodiment, the gap is selected for a final insert thickness that
measures a loading above the median of the predetermined range to
allow for soft tissue release back within the predetermined range.
In a step 1416, the gap is measured when the sensors measure
loading within the predetermined range. Alternatively, the dynamic
distractor can increase or decrease gaps incrementally that
correspond to available inserts. In a step 1418, the insert is
selected. As mentioned previously, the measured gap when the
loading is within the predetermined range may not correspond to a
final insert thickness. The surgeon can increase or decrease the
gap to an available insert thickness (and measure load in each
compartment) then select an insert based on subsequent steps of the
procedure to be implemented by the surgeon.
[0116] Steps 1420 and 1422 relate to adjustments made while a
spacer is inserted. In one embodiment, the spacer is the dynamic
distractor with one or more sensors. In a step 1420, data from the
sensors is transmitted to a processing unit. In a non-limiting
example, the processing unit is external to the dynamic distractor
and sensors. As disclosed herein, the processing unit can be part
of a notebook computer. The data from the sensors in the dynamic
distractor can be displayed for viewing by the surgeon and medical
team. In a step 1422, the surgeon can adjust the loading using soft
tissue release techniques with the dynamic distractor in place. In
one embodiment, the dynamic distractor can have a bellows or
removable skirt around the periphery of the device that prevents
debris from collecting within the interior. The bellows or
removable skirt is removed to allow access along the medial and
lateral periphery of the dynamic distractor and between the upper
and lower support structures of the dynamic distractor. Further
access for soft tissue release is provided by removing the handle
of the dynamic distractor or positioning the handle away from the
surgical area. Steps 1420 and 1422 can also be performed after the
leg is moved into the second relational position. In the knee
example, the leg is moved in flexion with the femur and tibia at
less than a 180 degree angle. For example, the leg is moved in
flexion at a 90 degree angle. Bone modification of the exposed
distal end of the femur can also be preformed to prepare a bone
surface for a femoral implant.
[0117] Steps 1424 and 1426 relate to adjustments made when
parameters are measured in more than one region. In the knee
example, measurements are made in the two knee compartments
corresponding to the medial and lateral condyles (natural or
artificial) in contact with the sensors. In a step 1424, the
loading is measured in each compartment. In one embodiment, the
measured loading in the two regions should be approximately equal.
The differential loading can be measured and then adjusted if
outside a predetermined differential load range. In general, the
side measuring the higher loading is adjusted. In a step 1426, soft
tissue release is performed to adjust the difference between the
loadings measured in each compartment. As disclosed herein, the
loading can be measured in real time as the release occurs. The
loading is then adjusted until the difference between the
compartments is within the predetermined differential load range
thereby adjusting the joint towards the optimum based on
measurement. Steps 1424 and 1426 can also be performed after the
leg is moved into the second relational position. It should be
noted that other adjustment methods can also be used in steps 1422
and 1426 if soft tissue release cannot produce the desired result.
In some cases, the dynamic distractor is removed for complete
access to the joint region allowing more substantial modification
to occur.
[0118] Steps 1428, 1430, 1432, 1434, 1436, and 1438 relate to
positioning and aligning the leg using the dynamic distractor. In
step 1428, the leg is positioned using position information
provided by the dynamic distractor. In one embodiment,
accelerometers in the sensors provide information on the angle of
the tibia in relation to the femur. Thus, the leg can be put
precisely in extension (e.g. a 180-degree angle between the femur
and tibia) and in flexion (less than 180-degree angle, for example
a 90 degree angle between the femur and tibia). In a step 430, the
positional information can be sent to the processing unit and the
information displayed on a display for viewing by the surgeon. The
surgeon can place the leg in extension or flexion to prepare or
shape the proximal end of the tibia or the distal end of the femur.
In steps 1432 and 1434, the surgeon identifies the mechanical axis
of the leg. In one embodiment, one or more lasers are coupled to
the handle of the dynamic distractor in the knee joint. As
mentioned previously, the handle of the dynamic distractor is
located overlying the center of the knee. In the step 1432, a first
laser emits a signal to a first target that is positioned
proximally to the center of the ankle. The line from center of the
ankle to the center of knee aligns with the mechanical axis of the
leg. The first target is positioned where it overlies the
mechanical axis on a plane corresponding to the beam from the first
laser. Similarly, in a step 1434, a second laser emits a signal to
a second target that is positioned proximally to the center of the
femoral head. A straight line from the center of the femoral head
through the center of the knee to the center of the ankle comprises
the mechanical axis of the leg. The second target overlies the
mechanical axis and is positioned on a plane corresponding to the
beam from the second laser. The surgeon can then measure the
misalignment of the leg to the mechanical axis and make corrections
appropriately.
[0119] FIG. 15 is an exemplary method 1500 for distracting surfaces
of the muscular-skeletal system in extension and in flexion in
accordance with an exemplary embodiment. The method can be
practiced with more or less than the number of steps shown and is
not limited to the order shown. In a step 1502, a distractor is
placed between surfaces of a muscular-skeletal system. As mentioned
previously, the distractor can be broadly used on the
muscular-skeletal system including but not limited to the spinal
column, knee, hip, ankle, shoulder, wrist, articulating, and
non-articulating structures. As disclosed above, the distractor
comprises a lift mechanism between a first support structure and a
second support structure. In one embodiment, a handle couples to
the lift mechanism to rotatably raise and lower the lift mechanism
thereby changing a gap between the surfaces of the support
structures. In general, the first and second supports structures
are placed between two surfaces of the muscular-skeletal system. In
a non-limiting example, to illustrate the principal, the distractor
can be used in joint repair or replacement surgery to separate
bones comprising the joint as they are prepared for an implant.
Examples are vertebrae of the spinal column, the distal end of the
femur and the proximal end of the tibia of a knee joint, or the
pelvis and the proximal end of the femur of the hip.
[0120] In a step 1504, the gap provided by the distractor is
changed and the muscular-skeletal system is placed in a first
relational position. The gap of the distractor can be changed under
the control of the surgeon thereby changing the spacing between the
two surfaces of the muscular-skeletal system being distracted. In
one embodiment, the gap corresponds to a thickness of one or more
components to be implanted in the muscular-skeletal system. The
distractor is likely to be initially placed between the two
surfaces having a minimum gap and then expanded to a predetermined
height or thickness. The muscular-skeletal system is placed in a
first relational position with the distractor inserted between the
two surfaces. The first relation position corresponds to the
positions of the surfaces and portions of the muscular-skeletal
system attached thereto.
[0121] In a step 1506, at least one parameter is measured with a
sensor. The muscular-skeletal system is in the first relational
position when parameter is measured by the sensor. In one
embodiment, the distractor includes a sensor for measuring a
parameter. For example, the sensor can provide accurate
measurements of parameters such as distance, weight, strain,
pressure, wear, vibration, viscosity, and density that relate to
the procedure being performed. The distractor further provides two
or more surfaces in contact with the muscular-skeletal system for
close proximity measurement by the sensor. As disclosed
hereinabove, the sensor can be self contained in a housing, can be
placed in a cavity on one or more of the distracting surfaces and
includes an exposed surface that can couple to the
muscular-skeletal system for sensing.
[0122] In a step 1508, the muscular-skeletal system is repositioned
to a second relational position. In a non-limiting example, the
second relational position corresponds to movement of the
distracted surfaces and portions of the muscular-skeletal system
attached thereto in relation to one another. The position of the
distracted surfaces in the second position is different from the
position of the distracted surfaces in the first position. The
distractor remains in place during positioning to the second
relational position. This provides the benefit of reducing surgical
time and stress on the patient. In general, the support structures
of the distractor and more specifically the surfaces of the support
structure allow natural movement of the muscular-skeletal in a
normal range of motion.
[0123] In a step 1510, at least one parameter is measured by the
sensor while in the second relational position. In one embodiment,
the distractor remains in place while the measurement is taken. The
surgeon or medical staff can compare measurement data with the
muscular-skeletal system in two different positions. Often the
measurement data will be similar throughout the range of motion or
differ by a known amount due to geometrical differences of the
position. Referring to a step 1518, the sensor can include a
transmitter for transmitting measurement data from the sensor to a
processing unit. The processing unit can be a logic circuit,
digital signal processor, microcontroller, microprocessor, or
analog circuitry. The processing unit can be part of a larger
system such as a multi-component custom system or a commercially
available notebook computer or personal computer. In a step 1520,
the measurement is displayed on a display. The data can be
processed by the processing unit and a GUI (graphical user
interface) integrated with the display to present the data, enhance
use of the data, interpret the data, and contemplate or detail
corrections that may be needed to be made based on the data. The
transmission of the data can occur as measurements over a range of
motion and at least in the first relational position and the second
relational position. In one embodiment, the distractor provides
measurement data on the amount of distraction or gap produced by
the device. This measurement data can also be transmitted along
with the relational position data of the muscular-skeletal system.
Thus, the distractor provides the benefit of measurement data being
taken with the sensor at different points of the range of motion
and at different gap heights without being removed.
[0124] In a step 1512, the sensor is placed on a surface of the
distractor. In one embodiment, the sensor is a disposable device.
The support structures of the distractor can have one or more
recesses or cavities for receiving a sensor on a surface of the
device. In particular, a cavity can be formed on a major surface of
a support structure that comes in contact with a surface of the
muscular-skeletal system during distraction. In a non-limiting
example, one or more sensors are placed in one more cavities prior
to insertion between the two surfaces of the muscular-skeletal
system. The sensors are activated and in communication with the
processing unit for taking measurements on the muscular-skeletal
system. In a step 1514, the sensor is coupled to a surface of the
muscular-skeletal system. As disclosed herein, the sensor can
include a major surface that is exposed and substantially parallel
to the major surface of a support structure. The sensor comes in
contact with the muscular-skeletal system as the two surface of the
muscular-skeletal system are distracted. Typically, as distraction
increases a compressive force by the two surfaces of the
muscular-skeletal system is applied to the two support structures
placing the sensor in intimate contact with the surface.
Alternatively, the sensor can be located on or in proximity to the
distractor if direct contact is not required for the
measurement.
[0125] In a step 1522, the alignment of at least one of the first
or second relational position is compared to a mechanical axis of
the muscular-skeletal system. Typically, the muscular-skeletal
system has optimal alignments that maximize performance of the
structure. The distractor can be used to measure misalignment to
the mechanical axis. The distractor utilizes at least one of the
surface being distracted to measure the misalignment. The
distracted surface of the muscular-skeletal system has a geometric
relationship with the mechanical axis. For example, the plane of
the distracted surface can be a specific angle from the mechanical
axis. Moreover, there can be specific landmarks of the surface that
such as a center point that further identify the relationship with
the mechanical axis.
[0126] In one embodiment, a plane of a portion of the surface of
the distractor is co-planar with the muscular-skeletal surface it
is contacting. This relationship is extended to a handle of the
distractor where a surface of the handle is co-planar to the
distracted surface of the muscular-skeletal system. The handle can
also extend from muscular-skeletal system at a location
corresponding to a landmark that corresponds to the mechanical
axis. For example, it can extend centrally or at a specific
position from the distracted surface. As disclosed hereinabove, a
drop rod can be attached to an opening in the handle to visually
and subjectively determine if alignment is within a predetermined
range. The drop rod can also be coupled to other fixtures coupled
to different areas of the muscular-skeletal system to measure
alignment. Alternatively, one or more lasers can be attached to the
handle of the distractor. The lasers are directed to one or more
targets that are located along the mechanical axis. The amount of
misalignment can be measured by the location where the beam hits a
scale on each of the target.
[0127] In a step 1524, the muscular-skeletal system is modified to
reduce the measured misalignment. In general, there will be an
acceptable range for misalignment to the mechanical axis.
Adjustments are made to reduce the error if the measurement is
outside the acceptable range. Modifications to the
muscular-skeletal system can take many forms. Material can be added
or removed from the bone structure. Soft tissue release of the
muscles, tendons, and ligaments can also be used to modify
alignment. Additionally, other structures and materials that are
both biological and artificial can be used to change or be added to
the muscular-skeletal system to bring the two surfaces into
alignment. After the modifications are performed, the alignment can
be rechecked to verify that the misalignment error is with an
acceptable range.
[0128] In a step 1526, the handle is used to direct the placement
of the distractor between the two surfaces of the muscular-skeletal
system. The handle of the distractor provides an external means for
the surgeon to locate and position the first and second support
structures of the distractor accurately in the muscular-skeletal
system. In one embodiment, the handle is coupled to a lift
mechanism that generates the gap between the first and second
support structures. In a step 1528, the gap height can be varied
using the handle. The handle is coupled to a shaft of the lift
mechanism. In a non-limiting example, the handle is rotated to
increase or decrease the gap of the distractor.
[0129] In a step 1530, the handle is moved away from the surgical
area. The distractor is designed to provide access to areas in
proximity to the two surfaces being distracted by the device. One
access area is anterior to the two surfaces of the distracted
muscular-skeletal system. Access is desirable to perform a surgical
procedure or other step with the distractor in place. A benefit of
the distractor is that the handle is hinged allowing it to be moved
away from the area where the surgical procedure is being performed.
Alternatively, in a step 1536, the handle is removed from the
distractor also giving unobstructed anterior access. The distractor
also has peripheral access and access between the first and second
support structures when a gap is created. In one embodiment, the
distractor has a bellows like skirt around the periphery of the
device that is inserted between the two surfaces of the
muscular-skeletal system. The skirt prevents materials or debris
from the procedure from getting between the first and second
support structures of the distractor. The skirt can be removed when
a procedure is performed requiring anterior, posterior, medial, or
lateral access. Alternatively, the periphery can be open and the
interior space between the first and second support structures can
be cleaned periodically to prevent build up of debris. The
distractor provides open space anterior, posterior, medially,
laterally, and between the first and second support structures
allowing the surgeon great latitude in performing surgical
procedures in proximity to the distracted area.
[0130] In a step 1532, the muscular-skeletal system is modified in
the first relational position. As disclosed above, modifications to
the muscular-skeletal system can take many forms. Bone
modification, soft tissue release, implants, adding artificial or
biological materials are but a few of the modifications that can be
made using the access provided by the distractor. Similarly, in a
step 1534, the muscular-skeletal system is modified in the second
relational position. In one embodiment, the distractor is not
removed during sensor measurement, movement through a range of
motion, and during the modification process thereby greatly
reducing the surgical time. Moreover, sensors in the distractor can
provide real time measurement of how the modifications are
affecting the distracted region. This instant feedback and
quantitative measurement allow fine adjustments to be made that
will greatly increase the consistency of orthopedic surgical
procedures.
[0131] FIG. 16 is an exemplary method 1600 for distracting surfaces
of the muscular-skeletal system in extension and in flexion in
accordance with an exemplary embodiment. The method can be
practiced with more or less than the number of steps shown and is
not limited to the order shown. Steps 1602, 1604, and 1606 are
respectively similar to steps 1502, 1504, and 1506 of FIG. 15 and
are not described here for brevity. In a step 1608, the measured
parameter is changed through modification of the muscular-skeletal
system. As mentioned previously, the distractor can be broadly used
on the muscular-skeletal system including but not limited to the
spinal column, knee, hip, ankle, shoulder, wrist, articulating, and
non-articulating structures. In one embodiment, the measurement and
the modification of the muscular-skeletal system occurs with the
distractor in place and the leg in extension.
[0132] In a step 1610, the muscular-skeletal system is repositioned
to a second relational position. As mentioned previously, the
position of the distracted surfaces in the second position is
different from the position of the distracted surfaces in the first
position. The distractor remains in place during positioning to the
second relational position. This provides the benefit of reducing
surgical time and stress on the patient. In general, the support
structures of the distractor and more specifically the surfaces of
the support structure allow natural movement of the
muscular-skeletal in a normal range of motion.
[0133] In a step 1612, at least one parameter is measured by the
sensor while in the second relational position. In a step 1614, the
measured parameter is changed through modification of the
muscular-skeletal system. The modification occurs with the
muscular-skeletal system in the second relational position. In one
embodiment, the distractor remains in place while moving the
muscular-skeletal system to the second relational position, during
sensor measurement, and modification of the muscular-skeletal
system. The surgeon or medical staff can compare measurement data
with the muscular-skeletal system in at least two different
positions. Referring to a step 1628, the sensor can include a
transmitter for transmitting measurement data from the sensor to a
processing unit. In a step 1630, the measurement is displayed on a
display. For example, the processing unit can be the microprocessor
of a notebook while the display is the screen of the notebook. The
data is transmitted in real time when a measurement is taken. In
other words, the data is transmitted, processed, and displayed
during the measurement and subsequent modification of the
muscular-skeletal system in the first relational position.
Similarly, the data is transmitted, processed, and displayed during
the measurement and subsequent modification in the second
relational position. The transmission of measured data can sent
wirelessly using a radio frequency signal.
[0134] In a step 1522, the alignment of at least one of the first
or second relational position is compared to a mechanical axis of
the muscular-skeletal system. Typically, the muscular-skeletal
system has optimal alignments that maximize performance of the
structure. The distractor can be used to measure misalignment to
the mechanical axis. The distractor utilizes at least one of the
surface being distracted to measure the misalignment. The
distracted surface of the muscular-skeletal system has a geometric
relationship with the mechanical axis. For example, the plane of
the distracted surface can be a specific angle from the mechanical
axis. Moreover, there can be specific landmarks of the surface that
such as a center point that further identify the relationship with
the mechanical axis.
[0135] In one embodiment, a plane of a portion of the surface of
the distractor is co-planar with the muscular-skeletal surface it
is contacting. This relationship is extended to a handle of the
distractor where a surface of the handle is co-planar to the
distracted surface of the muscular-skeletal system. The handle can
also extend from muscular-skeletal system at a location
corresponding to a landmark that corresponds to the mechanical
axis. For example, it can extend centrally or at a specific
position from the distracted surface. As disclosed hereinabove, a
drop rod can be attached to an opening in the handle to visually
and subjectively determine if alignment is within a predetermined
range. The drop rod can also be coupled to other fixtures coupled
to different areas of the muscular-skeletal system to measure
alignment. Alternatively, one or more lasers can be attached to the
handle of the distractor. The lasers are directed to one or more
targets that are located along the mechanical axis. The amount of
misalignment can be measured by the location where the beam hits a
scale on each of the target.
[0136] In a step 1616, the misalignment of the muscular-skeletal
system is measured. As disclosed above, the measurement can be made
using lasers and targets respectively coupled to the handle of the
distractor and located along the mechanical axis of the
muscular-skeletal system. In one embodiment, the misalignment is
referenced to at least one of the two surfaces being distracted by
the distractor. The alignment of the surface of the
muscular-skeletal system is compared to the mechanical axis. In a
step 1618, the muscular-skeletal system is modified to reduce the
measured misalignment. As mentioned previously, there is an
acceptable range for misalignment to the mechanical axis.
Adjustments are made to reduce the error if the measurement are
outside the acceptable range. In one embodiment, the corrections
can be checked in real time as the modifications are made to see
that the changes to the muscular-skeletal system are moving the
misalignment error to the acceptable range.
[0137] In a step 1620, the sensor measures load. In one embodiment,
the two surfaces of the muscular-skeletal system place a
compressive force across the first and second support structures of
the distractor. One or more sensors on the first and second support
structures of the distractor can be used to measure loading and the
distribution of loading. In a step 1622, the handle of the
distractor is moved away from a surgical area. In non-limiting
example, the surgical area corresponds to a region where muscles,
tendons, and ligaments couple the at least two surfaces of the
muscular-skeletal system together. The handle is moved to a
position such that modification to the soft tissue can take place.
In a step 1624, soft tissue is cut in the surgical area to reduce
loading applied by the two surfaces of the muscular-skeletal system
on the distractor. In general, the sensor can measure load,
pressure, or force. The distractor provides access for the surgeon
to make cuts to the soft tissue with the area distracted. The
sensor measures in real time allowing the surgeon to adjust the
load to an optimal value. In a step 1626, the handle can be removed
to further improve the anterior access.
[0138] FIG. 17 is an exemplary method 1700 for distracting surfaces
of a knee joint in extension and in flexion in accordance with an
exemplary embodiment. The method can be practiced with more or less
than the number of steps shown and is not limited to the order
shown. A knee joint implant procedure of the muscular-skeletal
system is used to illustrate the process of distraction. The knee
joint comprises the distal end of the femur and the proximal end of
the tibia. An artificial knee joint comprises a femoral implant, an
insert, and a tibal implant. The femoral implant is shaped similar
to and replaces the natural condyles at the distal end of the
femur. The insert has a bearing surface for receiving the condyles
and an inferior surface that mates and is retained by the tibial
implant. In general, the artificial knee joint mimics the natural
knee joint in operation once implanted.
[0139] All the steps for preparing a knee will not be disclosed for
brevity but are well known by one skilled in the art. The knee is
opened by incision to expose the distal end of the femur and the
proximal end of the femur. The patella is removed or moved away
from the knee joint region. The proximal end of the tibia is
prepared by cutting the bone. In one embodiment, the proximal end
of the tibia is prepared having a planar surface. In one
embodiment, the planar surface is cut perpendicular to the
mechanical axis of the leg. The distractor is then inserted into
the knee joint.
[0140] The distractor has a first support structure having a
superior surface for receiving the condyles of the femur and a
second support structure having an inferior surface for mating to
the prepared tibial surface. The shape of the support structures as
disclosed herein allows natural movement of the leg through the
range of motion with the distractor in place. In one embodiment,
two sensors are placed in the superior surface of the distractor
for measuring load in each compartment of the knee. A handle is
used to direct the first and second support structures into the
knee. The handle can be rotated to increase the gap of the
distractor to place the superior surface of the first support
structure in contact with the condyles of the femur and the
inferior surface of the second support structure in contact to the
tibial surface. More specifically, each condyle will contact a
surface of a corresponding sensor.
[0141] In a step 1720, the alignment of a surface of the distractor
is compared to the mechanical axis of the leg. The surface of the
distractor corresponds to a surface of the knee. In one embodiment,
the surface is the prepared surface of the tibia. Targets for leg
alignment can be placed overlying the mechanical axis of the leg.
Typically one target is placed in the ankle or foot region and a
second target is placed in the hip joint region near the femoral
head. The mechanical axis is a straight line from the center of the
femoral head through the center of the knee joint to the center of
the ankle. In one embodiment, handle extends from the knee joint at
a point that corresponds to the center of the knee joint. The
inferior surface of the second support structure is planar to the
tibial surface. Similarly, one or more surfaces of the handle of
the distractor is aligned to the inferior surface of the second
support structure thereby being co-planar to the tibial surface. As
disclosed hereinabove, lasers can be attached to the handle
pointing towards the ankle target and the hip target. As mentioned
previously, the tibial surface is prepared to be 90 degrees from
the mechanical axis of the leg. Misalignment from the mechanical
axis can be measured from where the beam of the laser hits the
target. A correctly aligned leg will hit each target at a point
representing the location of the mechanical axis. In a step 1722,
the measured misalignment can be reduced through modification of
the muscular-skeletal system. The modification can be to the bone,
soft tissue, additional implants or materials (artificial and
biological) that bring the femur and tibia into alignment with the
mechanical axis.
[0142] In a step 1702, the knee joint is distracted with the leg in
extension. The leg is in extension when the femur and tibia are
positioned having a 180-degree angle between them. A handle of the
distractor directs the support structures into the knee joint area.
The handle is rotated to increase a gap between the superior and
inferior surfaces until contact is respectively made to the
condyles of the femur and the surface of the tibia. The sensors in
each compartment of the first support structure are in
communication with an external processing unit. In one embodiment,
each condyle of the femur is in contact with a corresponding sensor
surface throughout the range of motion of the leg. The surgeon
positions the distractor such that the handle corresponds to the
center of the knee joint, which aligns with the mechanical axis of
the leg. In a non-limiting example, the leg alignment to the
mechanical axis can be measured and corrections made to reduce
misalignment if outside an acceptable range.
[0143] In a step 1704, a load is measured with the leg in extension
for at least one compartment of the knee. The data is received by
the processing unit and displayed on a display. For example,
accelerometers in the sensors can show relative position of the
femur to the tibia. In one embodiment, the femur and tibia are
shown on the display to provide visual information to the surgeon
on positioning. The angle between the femur and tibia can be
displayed as well as alignment of the leg to the mechanical axis.
The sensors include a measurement device such as a strain gauge to
measure load. A complete knee replacement will measure loading on
both compartments of the knee.
[0144] The distractor provides quantitative data that is used by
the surgeon to prepare the knee. In a non-limiting example, the
knee is distracted to a gap that corresponds to a combined insert
and tibial implant thickness (the distal end of the femur is
unprepared in the example). As is known by one skilled in the art,
inserts are available in different sizes and thicknesses. The
surgeon picks a size that is best adapted for the patient bone
dimensions. The surgeon prepares the bone surfaces for an
approximate combined thickness of the implants. For illustration
purposes a combined implant thickness of 20 millimeters could be
used. Typically, several insert thicknesses are suitable based on
the tibial cut and the resulting gap between the tibial surface and
the condyles of the femur. The sensor measurements are used to
select an appropriate range and allows fine-tuning of the loading
to within a very accurate range. For the full joint replacement,
the gap height of the distractor, angle between tibia/femur (180
degrees, leg in extension), the loading on each compartment at the
gap height, and the differential loading between the compartments
is transmitted and displayed for viewing by the surgeon.
[0145] In a non-limiting example, the surgeon may have to increase
or decrease the gap height of the distractor depending on the
sensor readings. The increase or decrease in gap height will
correspond to an available insert thickness. In one embodiment, the
surgeon adjusts the gap height to measure load on the high side of
a predetermined load range for each compartment. Selecting on a
high side reading allows for fine adjustments to the final load
value in a subsequent step. In general, the surgeon selects the
appropriate insert size for the knee implant.
[0146] In a step 1706, the leg is moved into flexion while the
distractor remains in the knee joint. As mentioned previously, the
distractor provides surfaces that allows movement of the joint
through the natural range of motion. This provides the benefit of
being able to prepare the leg for load, balance, and alignment in
more than one position using a single device. In one embodiment,
the gap height of the distractor remains in the selected height for
the leg in extension. Alternatively, the gap height of the
distractor can be reduced while moving the leg in flexion to a
final position and then readjusting the gap. In a non-limiting
example, the leg is moved in flexion to a position where the femur
and tibia form a 90-degree angle. In one embodiment, the surgeon
can move the leg while viewing femur/tibia angle on the screen to
get it precisely positioned.
[0147] In a step 1708, the load in at least one knee compartment is
measured with the leg in flexion. In a non-limiting example, the
gap height of the distractor in flexion is equal to the gap height
selected by the surgeon when the leg was in extension. The sensors
communicate with the processing unit providing the measured load in
each compartment, differential loading between compartments, and
the gap height to the surgeon with the leg in flexion. Thus, the
leg can be moved from extension to flexion with the distractor in
place. The sensors can measure load and differential loading in
different positions and gap heights that can be displayed on a
screen for the surgeon to view. The data is also stored in memory
for use.
[0148] In a step 1710, the handle of the distractor is moved from a
surgical area with the leg in extension. As mentioned previously,
the handle of the distractor includes a hinge to position the
handle away from a surgical area or can be removed to have anterior
access to the distracted area. The surgical area corresponds to the
muscle and ligaments coupling the femur to the tibia. The muscle
and ligaments in the surgical area are located laterally and
medially around the knee joint. A space is typically opened between
the first and second support structures when the knee joint is
distracted. Thus, the distractor enables soft tissue release by
providing access from multiple vantage points to the muscle and
ligaments with the device in place.
[0149] In a step 1712, the load in at least one compartment of the
knee is reduced with the leg in extension. The handle is positioned
to allow anterior and peripheral access to the soft tissue for
incision. The surgeon can also place a scalpel between the first
and second support structures for an interior or peripheral cut to
the soft tissue if needed. In a non-limiting example, the soft
tissue release can be performed when the leg is in extension after
the loading is measured and the gap adjusted to a height selected
by the surgeon. The soft tissue release can be performed on either
the lateral or the medial sides of the knee or on both sides. In
one embodiment, the soft tissue release is performed to bring each
compartment loading within a predetermine loading range. The sensor
data is transmitted, processed, and displayed in real time allowing
the surgeon to view the actual measured effect of each cut on the
loading in both compartments.
[0150] Referring to a step 1714, the load, force, or pressure in
both knee compartments are measured with the leg in extension. In a
step 1716, the measured load in each compartment is compared and a
differential loading is calculated. In a step 1718, the
differential loading between the two knee compartments is reduced
using soft tissue release with the distractor in the knee joint.
The surgeon can fine-tune the leg in extension to balance the
loading between compartments with the distractor in place. In one
embodiment, the surgeon can reduce the measured load on the side
reading the highest value and bring the differential loading down
within a predetermined differential loading range. In the example,
the absolute loading measured in each compartment has also been
reduced within a predetermined acceptable load range. As previously
disclosed, the gap generated by the distractor corresponds to an
available thickness insert of the artificial knee joint. The
display can provide indicators to the surgeon when the measured
load or the differential load is within their respective
appropriate ranges.
[0151] In a step 1722, the handle of the distractor is moved from a
surgical area with the leg in flexion. As mentioned previously, the
leg is positioned with the femur and tibia at a right angle. In a
step 1724, the load in at least one compartment of the knee is
reduced with the leg in flexion. The handle is positioned to allow
anterior and peripheral access to the soft tissue for incision. The
surgeon can also place a scalpel between the first and second
support structures for an interior or peripheral cut to the soft
tissue if needed. In a non-limiting example, the soft tissue
release can be performed when the leg is in extension after the
loading is measured and the gap adjusted to a height selected by
the surgeon. The soft tissue release can be performed on either the
lateral or the medial sides of the knee or on both sides. In one
embodiment, the soft tissue release is performed to bring each
compartment loading within a predetermine loading range. The sensor
data is transmitted, processed, and displayed in real time allowing
the surgeon to view the actual measured effect of each cut on the
loading in both compartments with the leg in flexion.
[0152] In a step 1726, the load, force, or pressure in both knee
compartments are measured with the leg in flexion. In a step 1728,
the measured load in each compartment is compared and a
differential loading is calculated. In a step 1730, the
differential loading between the two knee compartments with the leg
in flexion is reduced using soft tissue release with the distractor
in the knee joint. The surgeon can fine-tune the leg in extension
to balance the loading between compartments with the distractor in
place. In one embodiment, the surgeon can reduce the measured load
on the side reading the highest value and bring the differential
loading down within a predetermined differential loading range. In
the example, the absolute loading measured in each compartment has
also been reduced within a predetermined acceptable load range. As
previously disclosed, the gap generated by the distractor
corresponds to an available thickness insert of the artificial knee
joint. In the non-limiting example, the gap created by the
distractor in extension and flexion is the same. The display can
provide indicators to the surgeon when the measured load or the
differential load is within their respective appropriate ranges
when the leg is in flexion. The surgeon can take further
measurements on load and balance by moving the leg in different
positions of flexion and recording the values. Further adjustments
could be made to refine load and balance in these other flexion
positions with the distractor in place.
[0153] FIG. 18 is an exemplary method 1800 to place the
muscular-skeletal system in a fixed position for bone shaping in
accordance with an exemplary embodiment. The method can be
practiced with more or less than the number of steps shown and is
not limited to the order shown. A spacer is a device that as it
names implies spaces two surfaces apart from each other. A spacer
can have a fixed height or can be variable. In one embodiment, a
spacer has an inferior surface and a superior surface for coupling
to surfaces of the muscular-skeletal system. A spacer with a fixed
height is also known as a spacer block in the orthopedic field. A
spacer having variable height is known as a distractor.
[0154] In a step 1802, a spacer is placed between two surfaces of
the muscular-skeletal system. The spacer separates the two surfaces
of the muscular-skeletal system. In one embodiment, the spacer is
placed between two bones. The superior surface of the spacer
couples to a surface of a first bone and the inferior surface
couples to a surface of a second bone. There can be other material
or components between the superior and inferior surface of spacer
and the bone surfaces. Thus, the spacer separates the first and
second bone surfaces by at least the height of the spacer.
[0155] In a step 1804, a cutting block is coupled to an exposed
portion of one of the two bone surfaces. A cutting block is a
template for shaping a bone surface. It is typically fastened to a
bone surface and can have slots and openings for guiding surgical
tools such as a bone saw. In one embodiment, a cutting block is
used to shape a bone end for receiving one or more artificial
implant components or material. In many cases, the position of the
cutting block is not arbitrary but has to have precision alignment.
For example, when performing a joint replacement, the cutting block
has to be positioned having one or more alignments to the
muscular-skeletal system. Misalignment can cause joint failure and
premature wear. An illustration of alignment will be disclosed in
more detail by example hereinbelow.
[0156] In a step 1806, the spacer is coupled to the cutting block
to rigidly position the two surfaces in a predetermined position.
Cutting blocks are typically designed to be used to shape the bones
with the two surfaces and more specifically the bones having the
surfaces in a specific position and alignment. In one embodiment,
the spacer is fixed in position to at least one of the bone
surfaces. The spacer can be under compressive force due to muscle,
ligaments and tendons coupling the first and second bones together.
Alternatively, the spacer can be temporarily attached to one of the
surfaces. For example, a surgical screw or pin can be used to fix
the spacer position. If the spacer is a distractor, the compressive
force can be adjusted by increasing or decreasing the height
between the superior and inferior surfaces. The spacer can allow
the two bones to move in relation to one another in a natural range
of motion without movement of the device to the bone surface. The
spacer and the cutting block are couple together to prevent
movement of the first bone, second bone, bone surfaces, and cutting
block. Coupling the spacer to the cutting block stabilizes the
cutting block and keeps the first and second bones in a fixed
relation to one another while the bone surface is shaped.
[0157] In a step 1810, the misalignment of at least one of the
surfaces is measured in relation to a mechanical axis of the
muscular-skeletal system. In general, alignment of the
muscular-skeletal system is critical to obtain optimal performance
and longevity. In fact, many problems that end up requiring surgery
are due to misalignment or deformity that causes premature wear or
damage to the muscular-skeletal system that can directly or
indirectly result in a disability or health problem. Implanted
devices and artificial joints follow similar constraints from a
geometric standpoint since many mimic the natural device. Thus, the
surgeon needs affirmation that the alignment of the
muscular-skeletal system while modifying bone and soft tissue to
receive implanted components. Typically, at least one of the bone
surfaces has a relationship with a mechanical axis of the
muscular-skeletal system. The mechanical axis is an optimal
alignment of the bone or bone surface to another portion of
muscular-skeletal system. In a non-limiting example, the bone
surfaces and the thus the bones having the bone surfaces have an
optimal alignment. This optimal alignment is known as the
mechanical axis.
[0158] In one embodiment, a surface or feature of the handle
corresponds to a surface of the muscular-skeletal system. This
relationship can be used to compare the orientation of the surface
or feature to a mechanical axis. The superior or inferior surface
of the spacer couples to the surface (or reference surface). The
surface of the spacer is shaped similarly to the reference surface.
For example, if the reference surface of the muscular-skeletal
system is planar, the spacer surface is also made planar and has a
relational position of being co-planar or parallel to the reference
surface. A feature or the surface of a feature such as an opening,
recess, mounting structure can have a specific orientation to the
reference surface. For example, an opening can have an orientation
that is perpendicular to the reference surface. Thus, the opening
will extend in a direction approximately perpendicular to the
muscular-skeletal reference surface on which the spacer is coupled.
The handle can have one or more surfaces or features made to have
specific relational positions to one or both of the spacer
surfaces. For example, at least one surface of the handle can be
made co-planar to the spacer surface corresponding to the
muscular-skeletal reference surface. The surface on the handle can
be used to create features that have specific positional
relationships to the plane of the muscular-skeletal reference
surface to aid in determining misalignment. Measurement of
misalignment will be discussed in more detail hereinbelow.
[0159] As disclosed hereinabove, the mechanical axis can be defined
by placing targets overlying the patient that align to the axis or
to reference points of the body. For illustrative purposes, the leg
in extension will be used to describe a mechanical axis of the
muscular-skeletal system for a knee joint replacement. The
mechanical axis of the leg in extension is a straight line from the
center of the femoral head, to the center of the knee joint, and
continuing to the center of the ankle. The targets are placed above
the mechanical axis and typically near the ankle region and the
center of the femoral head. In one embodiment, the handle is
aligned with the center of the knee joint and extends vertically
from the knee. In a non-limiting example, a feature such as a
center of at least one opening or a recess in the handle is
geometrically aligned to the knee center and corresponds to a point
on the mechanical axis. The mechanical axis corresponds to a
straight line from a point on the ankle target (e.g. ankle center),
to a point on the handle, and extending to a point on hip target
(e.g. center of femoral head). Extending a plane of the mechanical
axis vertically (e.g. 90 degrees to the horizontal plane) with the
leg in extension would intersect the center of the feature on the
handle. In the example, the proximal end of the tibia is prepared
by the surgeon as a flat surface. Ideally, the mechanical axis of
the intersects the plane of the prepared tibial surface at a right
angle. In a non-limiting example, lasers are coupled openings or
recesses in the handle of the spacer. The lasers point towards the
ankle target and the hip target. The lasers are pointed at a
90-degree angle from the plane of the prepared bone surface. Thus,
misalignment can be measured from the targets as the difference
angle between the point where beams hit the target and the
identified point on each target corresponding to the mechanical
axis.
[0160] In a step 1812 the muscular-skeletal system is modified to
reduce the misalignment within a predetermined range. Once the
misalignment is measured the surgeon can determine if modification
to the muscular-skeletal system is required and what type of
modification is suitable to reduce the error. In general, keeping
the misalignment within a predetermined range will improve
consistency of the surgery. Implant manufacturers can use the
surgical data to determine the sensitivity of misalignment to
rework, patient problems, and implant longevity.
[0161] In a step 1814 the spacer is aligned between the two
surfaces where a handle of the spacer intersects the mechanical
axis. Typically, the spacer alignment occurs before the
misalignment to the mechanical axis is measured. As disclosed
above, the spacer is part of an alignment system. The spacer has a
predetermined position or alignment between the first and second
bone surfaces and more specifically on the reference bone surface.
In one embodiment, the handle extends from the spacer and
intersects the mechanical axis. In the non-limiting example, the
spacer is placed on the prepared tibial surface such that a
superior surface of the spacer mates with the condyles of the
femur. Moreover, the handle extends centrally from the spacer with
the leg in extension corresponding to the center of the knee joint
(e.g. a point on the mechanical axis).
[0162] In a step 1816, a rod is coupled to the handle. The handle
has a known relational positioning to the mechanical axis within
the predetermined range as described hereinabove. In one
embodiment, the rod fits into an opening in the handle. The rod can
be fastened to the handle. For example, portions of the rod and the
opening in the rod can be threaded. Alternatively, the rod can be
held in place by a powerful magnet, clamp, screw, or other means.
In general, the rod is rigid and projects the positional
relationship of the handle (e.g. the bone reference surface). In
the knee example, the tibia and femur are placed in flexion. More
specifically, the tibia and femur are positioned having a 90-degree
angle between the bones. The cutting block is on the exposed
portion of the distal end of the femur to be shaped. Thus, the
entire distal end of the femur is not shaped in this position.
[0163] In a step 1818, the rod is coupled to the cutting block. The
rod is then coupled to both the handle and the cutting block. In
one embodiment, the cutting block has a channel approximately the
same diameter as the rod. The rod is placed in the channel of the
cutting block. The rod fixes the position of the spacer and the
cutting block. As mentioned previously, the spacer and the handle
is within a predetermine range of the mechanical axis. In a
non-limiting example, the rod extends along the mechanical axis.
Placing the rod into the channel aligns the cutting block to the
mechanical axis. The rod fixes the relational position of the first
bone surface to the second bone surface. In the embodiment, the
femur and tibia are aligned to the mechanical axis and positioned
perpendicular to each other.
[0164] In a step 1820, the gap of the spacer is changed. In one
embodiment, the spacer is a dynamic distractor. The dynamic
distractor includes sensors to measure loading. As the gap of the
distractor is increased the first and second bone surfaces apply a
compressive force on the spacer. The muscle, ligaments, and tendons
couple the two bones holding them together under tension. The gap
can be adjusted to be within a predetermined measured loading range
(at the distracted gap height).
[0165] In a step 1822, the bone surface is shaped. The cutting
block is used as a template to direct a saw blade to shape the
bone. With the rod rigidly holding the bone surfaces in place the
cutting block is stabilized and in alignment with the mechanical
axis. In the knee example, the exposed portion distal end of the
femur can be shaped with the leg in flexion. The shaped surface can
receive an implant that will be aligned correctly to the mechanical
axis as well as the femur and tibia surfaces.
[0166] FIG. 19 is an exemplary method 1900 of measuring the
muscular-skeletal system in accordance with an exemplary
embodiment. The method can be practiced with more or less than the
number of steps shown and is not limited to the order shown. In a
non-limiting example a spacer is a device that separates two
surfaces of the muscular-skeletal system. The spacer has an
inferior surface and a superior surface that contact the two
surfaces. The spacer can have a fixed height or can have a variable
height. A fixed height spacer is commonly called a spacer block.
The variable height spacer is known as a distractor. The use of
spacer disclosed herein includes the spacer block and the
distractor. In one embodiment, a handle extends from the spacer and
typically resides outside or beyond the two surface regions being
distracted. The handle is used to direct the spacer between the two
surfaces. In one embodiment, the handle operatively couples to a
lift mechanism of the distractor to increase and decrease a gap
between the superior and inferior surfaces of the spacer. The
spacer and handle is part of a system to measure alignment of the
muscular-skeletal system. In one embodiment, at least one of the
surfaces of the muscular-skeletal system that contacts the spacer
has an optimal alignment to a mechanical axis of the
muscular-skeletal system. The system measures the surface to
mechanical axis alignment. In a non-limiting example, the surface
can be corrected by a surgeon when the surface is misaligned to the
mechanical axis outside a predetermined range.
[0167] A surface or feature of the handle has a relational position
to the (reference or alignment) surface of the two surfaces that
the spacer contacts. In one embodiment, the reference surface of
the muscular-skeletal system is a planar surface. The surface of
the spacer contacting the reference surface of is also planar and
thus has the relational position of being planar or co-planar when
coupled thereto. Similarly, the handle is attached or coupled to
the spacer block or distractor having a relational position to the
surface of the spacer that contacts the reference surface.
Typically, the relational position of the surface or feature on the
handle is co-planar or perpendicular to the surface of the
spacer.
[0168] The two surfaces of the muscular-skeletal system are
typically positioned in predetermined relation before measuring
misalignment to the mechanical axis. The predetermined relation
typically corresponds to a natural position of the
muscular-skeletal system. For example, a common position is the
tibia positioned 180 degrees from the femur, which is commonly
known as a leg in extension. In this example, the reference surface
is a proximal tibial surface of the tibia. In one embodiment, the
proximal tibial surface is a planar surface prepared by the
surgeon. Ideally, the tibial surface is formed perpendicular to the
mechanical axis with the leg in extension. A measurement of the
tibial surface to the mechanical axis is performed to verify that
it is within a predetermined range or specification. Similarly, a
measurement is often taken with the muscular-skeletal system in a
second predetermined relation. The second predetermined relation is
typically at a different point in the range of natural motion. For
example, the leg in extension with the tibia positioned 90 degrees
from the femur. One or more sensors such as accelerometers can be
use to measure the relational positioning of the two surfaces of
the muscular-skeletal system.
[0169] In one embodiment, a feature such as an opening or cavity is
formed in the handle. The opening or cavity has a relational
positioning to the reference surface when the spacer block or
distractor is placed between the two surfaces of the
muscular-skeletal system. In a non-limiting example to illustrate
the relational positioning, the opening or cavity is perpendicular
to the plane of the reference surface. In the example where the
mechanical axis is ideally perpendicular to the reference surface a
rod is placed in the opening or cavity. The rod is directed
perpendicular to the plane of the reference surface. A comparison
of the direction of the rod to the mechanical axis yields
misalignment of the reference surface to the ideal. The surgeon can
use the rod with landmarks that identify the mechanical axis to
make a visual determination of alignment. Alternatively, the rod
can be used to measure an angle difference between the mechanical
axis and the actual muscular-skeletal alignment. Furthermore, the
rod can include one or more sensors for measuring a parameter of
the muscular-skeletal system including alignment.
[0170] In another embodiment, targets are placed on the
muscular-skeletal system aligned with the mechanical axis. An axis
point or axis line on the target aligns with the mechanical axis. A
laser is placed in the opening or cavity on the handle. In a
non-limiting example, the center of the opening or cavity
corresponds to an axis point on the mechanical axis. The mechanical
axis is a straight line between the center of the opening and one
or more targets. The beam of the laser is directed to the target.
Using the example above, the beam is directed perpendicular to the
plane of the reference surface to the target. The position where
the beam hits the target corresponds to misalignment of the
reference surface to the mechanical axis. The misalignment results
in the beam hitting the target on either side of the axis point or
line. In a similar fashion the location of the beam on the target
could also be used to determine if the reference surface has a
slope by viewing where the beam hits the target in an opposite
plane. For example, if the misalignment measurement is on a
horizontal plane relative to the axis point, a slope of the
reference surface can correspond to the beam location on a vertical
plane or above/below the axis point.
[0171] In a step 1902, two surfaces of the muscular-skeletal system
are distracted with a spacer. The gap between the two surfaces can
be varied with the distractor. In a step 1904, an alignment aid is
coupled to a handle of the distractor. The misalignment of a
surface (e.g. reference surface) of the two surfaces to a
mechanical axis is measured with an alignment aid that is coupled
to a handle of the distractor. The alignment aid is coupled to a
surface or feature of the handle of the distractor that has a
relational position to the reference surface. In one embodiment, an
alignment aid can be a laser and at least one target. Referring to
a step 1926, at least one laser is coupled to the handle of the
distractor. In one embodiment, the at least one laser is coupled to
a feature such as an opening or cavity. In a step 1928, at least
one target is coupled to the muscular-skeletal system. In general,
the at least one target can be placed overlying the
muscular-skeletal system such in a location corresponding to an
axis point of the mechanical axis. An axis point on the target
aligns to the mechanical axis. The beam from the laser hits the
target. The point where the beam hits is compared to the axis point
of the target that corresponds to the mechanical axis. The target
can have a scale that measures misalignment of the surface to the
mechanical axis. As disclosed above, the direction of the laser
corresponds to the surface of the muscular-skeletal system.
[0172] In a step 1906, the two surfaces of the muscular-skeletal
system are placed in a first position. The misalignment of the
surface to the mechanical axis is measured. In a step 1908, the
misalignment is corrected if the measurement is outside a
predetermined range. In general, data generated by this system can
yield significant information on how misalignment affects the
muscular-skeletal system. The data can be used to further identify
the optimal predetermined range that minimizes the effect of
misalignment and consistently produces a positive outcome. In a
step 1910, the gap or the space between the inferior and superior
surfaces of the spacer is measured. In a step 1912, a force,
pressure, or load applied by the two surfaces of the
muscular-skeletal system on the distractor is measured. One or more
sensors can be placed in the superior or inferior surfaces to
measure a parameter such as but not limited to force, pressure, or
load. The two surfaces of the muscular-skeletal system apply
pressure or force to the superior and inferior surfaces of the
spacer and more specifically on at least one sensor on either
surface of the distractor. The measurements of steps 1908, 1910,
and 1912 are completed with the muscular-skeletal system in the
first position. As mentioned above, the first position is typically
a geometrically significant position of the muscular-skeletal
system that allows comparison to the mechanical axis. The
measurement data is transmitted to a processing unit for viewing on
a display and for long-term storage. The system allows for real
time measurement if and when the muscular-skeletal system is
modified with the distractor in place.
[0173] The following measurements steps are similar to the
measurements in the first position described above. In a step 1916,
the two surfaces of the muscular-skeletal system are placed in a
second position. The misalignment of the surface to the mechanical
axis can be measured in the second position to verify alignment. In
a step 1918, the misalignment is corrected in if the measurement is
outside a predetermined range. In a step 1920, the gap or the space
between the inferior and superior surfaces of the spacer is
measured. In a step 1922, a force, pressure, or load applied by the
two surfaces of the muscular-skeletal system on the distractor is
measured. The measurements of steps 1918, 1920, and 1922 are
completed with the muscular-skeletal system in the second position.
As mentioned above, the second position is also a geometrically
significant position of the muscular-skeletal system that allows
comparison to the mechanical axis. The measurement data is
transmitted to the processing unit. The system allows for real time
measurement in the second position.
[0174] FIG. 20 is an exemplary method 2000 of a disposable
orthopedic system in accordance with an exemplary embodiment. The
method can be practiced with more or less than the number of steps
shown and is not limited to the order shown. In a step 2002, at
least one parameter of the muscular-skeletal system is measured
with a sensor. As disclosed hereinabove, the sensor provides
accurate measurements of parameters such as distance, weight,
strain, load, pressure, force wear, vibration, viscosity, and
density. In one embodiment, the sensor is a disposable sensor. In a
non-limiting example, the disposable sensor is adapted to an
orthopedic device such as a tool or implantable component. The
sensor is sterilized and placed in a package that maintains
sterility. The sensor is typically contaminated with biological
material when used to measure the muscular-skeletal system during a
surgical procedure. In a step 2004, the sensor is disposed of after
use. The sensor is disposed of as biological waste if contaminated
by biological material during the procedure. Packaging of a single
use device greatly reduces cost, as the housing does not have to
withstand repeated cleanings. Moreover, it eliminates the cost of a
sterilization process. In a non-limiting example, the sensor is
used in orthopedic surgery and more specifically to provide
intra-operative measurement during joint implant surgery.
[0175] In a step 2022, the sensor is powered. In one embodiment,
the sensor is not powered until it is used. The sensor can have a
temporary power source that powers the device for a procedure. A
charger can be provided to charge the unit up prior to use. The
power source can be internal to the sensor to prevent issues with
sterility. The temporary power source can sustain the device for a
predetermined period of time that is sufficient for the procedure
but prevents reuse of the device. The sensor is in communication
with a processing unit. In one embodiment, the processing unit is
located external to the sensor. In the surgical example, the
processing unit is located outside of the immediate surgical area.
For illustration purposes, the processing unit is a microprocessor
of a notebook computer.
[0176] In a step 2024, patient information is inputted to the
processing unit. The patient information can input through a
variety of methods. For example, the information can be typed in,
scanned in, downloaded via radio frequency tag, or verbally
transmitted, recorded, and converted. The patient information can
be displayed on a screen of the notebook computer. The patient
information can include personal, medical, and specific information
related to the procedure.
[0177] In a step 2026, a reader is coupled to the processing unit.
The reader can be wired or wireless. In a step 2028, the reader is
used to scan in information pertaining to the procedure. In one
embodiment, the reader is used to scan in components of the system
such as the sensors, alignment aids, implant components, and other
devices prior to use. In a non-limiting example, the information
can be used for identification of the specific components (e.g.
serial numbers) used during the procedure. The information can be
used for billing, patient records, long term monitoring of
components, and component recall.
[0178] In a step 2006, the sensor is placed between two surfaces of
the muscular-skeletal system. The sensor measures a parameter in
proximity to the surfaces of the muscular-skeletal system. In one
embodiment, the two surfaces are exposed by incision. For example,
the sensor has a small form factor allowing it to be placed in or
on a spacer. A spacer separates the two surfaces of
muscular-skeletal system. Examples of a spacer are a spacer block
or a distractor. In a non-limiting example, a joint of the
muscular-skeletal system is exposed. One or more of the joint
surfaces can be shaped or prepared by the surgeon. The spacer block
or distractor is placed between the joint surfaces of the
muscular-skeletal system. The sensor can have an exposed surface
that will contact at least one of the two surfaces.
[0179] In a step 2008, a load, force, or pressure applied by the
two surfaces on the sensor is measured. For example, the spacer
block or distractor distracts the joint of the muscular-skeletal
system. A measurement of the load, force, or pressure is measured
by the sensor for a spacing or gap. The gap is the distance between
the two surfaces of the muscular-skeletal system. In a step 2016, a
gap can be varied between the two surfaces of the muscular-skeletal
system with the spacer in place. In one embodiment, the gap is
varied by a distractor between the two surfaces. The distractor
includes a lift mechanism that can increase or decrease a gap
between the two surfaces. The sensor can measure one or more
parameters at each gap height.
[0180] In a step 2010, the sensor is placed in a cavity of a
surface of a spacer. In general, a spacer has a superior and
inferior surface. The superior and inferior surfaces are placed
between the two surfaces of the muscular-skeletal system. The
superior and inferior surfaces come in contact with the two
surfaces of the muscular-skeletal system under distraction. In one
embodiment, one of the inferior or superior surfaces of the spacer
have a cavity or recess for receiving the sensor. The sensor is
placed in the cavity exposing a surface of the sensor. The surface
of the sensor can be planar with the surface of the spacer. As
disclosed above, the spacer can be placed between the two surfaces
of the muscular-skeletal system such that the surface of the sensor
is in proximity or in contact with one or both of the surfaces.
[0181] In a step 2012, the sensor is removed from the cavity or
recess. The sensor can have a feature that simplifies removal from
the superior or inferior surface of a device. For example, the
sensor can have a tab, indentation, or surface feature that allows
removal by hand or with a tool. Alternatively, the device in which
the sensor is placed can have a mechanism to push the sensor out of
the recess. In a step 2014, the sensor is disposed of after being
removed from the cavity or recess.
[0182] In a step 2018, an alignment of a surface to a mechanical
axis is measured with an alignment aid. In general, at least one of
the two surfaces of the muscular-skeletal system has an alignment
with a mechanical axis of the muscular-skeletal system. The
alignment to the mechanical axis needs to be preserved or corrected
during the procedure. Similar to the sensor above, components of
the alignment aid are designed for a single use. In one embodiment,
the mechanical axis is identified. Similarly, the surface of the
muscular-skeletal system is compared to the mechanical axis. The
difference between the mechanical axis and surface of the
muscular-skeletal system is a measure of the misalignment.
Adjustments to the muscular-skeletal system can be performed to
reduce misalignment within a predetermined range. In a step 2020,
at least one component of the alignment aid is disposed of after
the procedure is completed.
[0183] FIG. 21 is an exemplary method 2100 of a disposable
orthopedic system in accordance with an exemplary embodiment. The
method can be practiced with more or less than the number of steps
shown and is not limited to the order shown. In a step 2102, an
alignment of a surface to a mechanical axis is measured with an
alignment aid. In general, a mechanical axis is identified by the
alignment aid. The mechanical axis is then compared to an alignment
of one or more surfaces or structures of the muscular-skeletal
system. Ideally, the difference or misalignment of the surfaces or
structures to the mechanical axis should be within a predetermined
range that places the surfaces or structures in an optimal
muscular-skeletal kinematic setting.
[0184] In a non-limiting example, targets and more specifically a
point on each target correspond to points on the mechanical axis.
The targets are coupled to the muscular-skeletal system in
proximity to the surfaces of the muscular-skeletal system. The
surfaces can be part of structures of the muscular-skeletal system
such as bones, muscles, ligament, tendons, and cartilage. The
structures corresponding to the surfaces can have a relational
positioning in 3D space that relate to the position of the surfaces
to each other. In one embodiment, the surface is between the
targets. Alternatively, the targets can be placed having an
unobstructed path to the surface that allows measurement. The
targets can also align having a more complex geometry to represent
the mechanical axis. One or more lasers are mounted at a height
where a beam from a laser will hit the target unless grossly
misaligned. The laser is mounted having a predetermined positional
relationship to the plane of the surface. For example, the laser is
directed 90 from the plane of the surface corresponding to a
direction of the mechanical axis. The targets can have calibration
markings to indicate a measure of misalignment. The beam from the
laser will hit the point on each target if the plane of the surface
is aligned correctly to the mechanical axis. Conversely, the
distance from the point on each target is representative of the
misalignment. The calibration marking where the beam hits
represents the misalignment. Adjustments to the muscular-skeletal
system can be performed to reduce misalignment within a
predetermined range. In a step 2104, at least one component of the
alignment aid is disposed of after the procedure is completed. For
example, the targets or lasers that are within the surgical
field.
[0185] In one embodiment, the alignment is performed with a
distractor between the two surfaces of the muscular-skeletal
system. The distractor separates the surfaces of the
muscular-skeletal system. In a step 2122, the two surfaces of the
muscular-skeletal system are distracted when measuring alignment.
The distractor can vary the gap between the two surfaces of the
muscular-skeletal system allowing measurements to be taken with
varying gap heights.
[0186] In a step 2106, at least one parameter of the
muscular-skeletal system is measured with a sensor. As disclosed
hereinabove, the sensor provides accurate measurements of
parameters such as distance, weight, strain, load, pressure, force
wear, vibration, viscosity, and density. In one embodiment, the
sensor is a disposable sensor. In a step 2108, the sensor is
disposed of after use. The sensor is disposed of as biological
waste if contaminated by biological material during the procedure.
A disposable sensor provides data for providing quantitative data
on the procedure without the large capital expenditure required for
traditional measuring equipment.
[0187] In general, data is collected relevant to the procedure. For
example, patient information and component information can be
collected and stored in an electronic format prior to the procedure
being performed. Component information can relate to products used
in the procedure such as serial number, date of production, model
number, and other related data that identifies the product. In a
step 2014, the sensor is powered. In one embodiment, the sensor is
not powered until it is used. Once enabled, the sensor can
establish communication with a processing unit. The processing unit
can be a collection point for information. The processing unit is
coupled to memory that can store information locally or send the
information to a database. Similarly, the sensor can have
information pertaining to the sensor product stored in memory. The
sensor can send this information to the processing unit as part of
the information collection process. In a step 2116, patient
information is input and provided to the processing unit. The
patient information can be input through a variety of methods. For
example, the information can be typed in, scanned in, downloaded
via radio frequency tag, or verbally transmitted, recorded, and
converted. The patient and component information can be displayed
on a screen coupled to the processing unit for use by the surgeon
or other healthcare providers. The patient information can be
encrypted to prevent access by unauthorized people. The patient
information can include personal, medical, and specific information
related to the procedure. In a step 2118, a reader is coupled to
the processing unit. The reader can be wired or wireless. In a step
2120, the reader is used to scan in information pertaining to the
procedure. In one embodiment, the reader is an alternate approach
of data collection of components and information. The reader is
used to scan and input information displayed on components or
packaging of components. The information can be used for billing,
patient records, long term monitoring of components, and component
recall.
[0188] In a step 2110, data measured by the sensor is transmitted
to the processing unit. The system dynamically measures a parameter
of the muscular skeletal system. For example, the system can
measure the parameter when the muscular-skeletal system is placed
in different positions whereby the position of the surfaces also
differs. Another example is modification of the muscular-skeletal
system. The sensor reading adjusts as the modification of the
muscular-skeletal system changes the parameter being measured. In a
step 2112, the data is displayed in real time on the display. In
one embodiment, the sensor transmits data as soon as a measurement
is taken. The data is then processed by the processing unit and
displayed in a format that aids the surgeon or healthcare worker.
Thus, any change in the parameter is stored and displayed while the
sensor is enabled.
[0189] In summary, the invention describes a system to define the
joint gap, bone preparation, alignment, load, and balance by
measurement. Furthermore the surgeon obtains the information in
real time from the system while soft tissue release and alignment
is being performed. The graphic user interface can be in the device
itself or integrated with a processing unit and display in the
operating room. The sensors can be incorporated into tools and
equipment for measuring the muscular-skeletal system
pre-operatively, intra-operatively, post-operatively, and long
term. The sensors or sensor system is in communication with a data
registry and repository to generate statistically significant data
that can be used as clinical evidence. The data repository and
registry further includes information used in evidentiary based
orthopedic medicine. This invention while intended for use in the
medical field and more specifically orthopedics uses a knee
application to illustrate principles of the system and method for
illustrative purposes only and can be similarly adapted for the
hip, shoulder, ankle, spine, as well as to measure other parameters
of a biological system.
[0190] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
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